'Back to the Future' fans #AskBobGale: Your toughest questions answered

You asked, screenwriter Bob Gale answered.

(CNN)Three decades before flat screen TVs, voice-activated apps, and video conferencing were invented, they were already being dreamed up by 'Back to the Future' screenwriter Bob Gale.

Indeed, it's a little unnerving to think just how many things Gale got right about 2015.
To mark the 30-year anniversary of the famous film trilogy, we asked you to send in your burning "Back to the Future" questions for Gale, using the Twitter hashtag #AskBobGale or leaving a comment on our call-out.
Screenwriter Bob Gale.
We were inundated with questions, with the best appearing here.
    To delve a little deeper into Gale's understanding of time travel, personal inspiration, and advice for up-and-coming screenwriters, see the full questions and answers below.

    Your #AskBobGale questions in full

    "What influence do you think Back to the Future has had on time travel cinema?" -- Dr. Sorcha Ní Fhlainn
    Bob Gale: "When Bob Zemeckis and I were trying to get 'Back to the Future' (BTTF) off the ground, we were repeatedly told 'time travel movies don't make any money.'
    So BTTF certainly changed that theory! We've been gratified to hear that people point to our trilogy as an example of 'time travel done right,' in which the rules are defined and understandable, and the stakes are clear. So it's become a benchmark in the genre, and it's meant that studios aren't afraid to make them."
    BG: "They would be sitting at Starbucks, complaining that we don't have flying cars or hoverboards!"
    BG: "The characters! Interesting characters are what keeps audiences interested in the story, and it's why movie stars are paid so much.
    People like to see people, and the characters are our gateway into the story. I also think a great -- or at least an appropriate -- ending is very important."
    If you had the opportunity to go back in time to change a part of the movie, what would you change?— Rafael Wilhelm
    BG: "The only things that bother me (just a little) are technical, such as the fact that the flames don't go exactly thru Marty's legs at the Twin Pines Mall.
    And we were never truly satisfied with the 'hole in the hand' shot during 'Earth Angel.' But Bob Zemeckis and I are very happy with all three movies the way they are, and we would never consider altering them. They are a product of their time, and we intend to leave well enough alone."
    BG: "Well, besides the time machine, we don't actually see many of Doc's inventions. We knew you could build the dog food machine -- after all, we built one for the movie -- but there wouldn't be much demand for it. We certainly didn't expect there to be a working brainwave machine.
    The devices Doc has in 2015 weren't actually invented by Doc -- we presumed these were "off the shelf" purchases. So if you're asking about those, we thought the biometric devices would happen (and we were right), we thought flat screen TVs and home video conferencing would happen (and we were right), we didn't expect drones would happen (but they did), we expected weather prediction would improve.
    We expected there would be a lot of voice-activated technology (we were right), and we expected that medical information would be accessible through a person's finger print (which is almost reality). We did not expect there would be fusion power or flying cars or hoverboards, but people are trying to create all of these."
    BG: "I wouldn't! I couldn't! Back to the Future (BTTF) was co-created and co-written by my good friend, director Robert Zemeckis, and there's no better director alive today!
    The movies are directed brilliantly on every level, so no one should even think about someone else directing them!"
    BG: "I'm disappointed that the scourge of terrorism and fanaticism has continued unabated, that our politicians and world leaders haven't gotten any better, and I'm especially disappointed that the space program seems to have stalled.
    And although part of me wishes we had flying cars, it seems we still have enough trouble driving in two dimensions, so maybe it's good that we're not asking people to drive in three.
    On the plus side is the marvel of the internet. As a writer and researcher, I love having access to so much information.
    And we certainly didn't foresee the smart phone, and I'd have to say that it's the most amazing device we have today -- and one that has truly changed society and how people relate to each other.
    The ability to stream movies on demand is also a fabulous development for everyone who loves movies."
    BG: "In Part II, in 1955, we have two Docs running around. One of them is about 40, and he's living in 1955 as the natural course of his life.
    The other is the Doc from 1985, and he's about 70. It's the 70-year-old Doc that gets sent back to 1885, and there's a time line where that Doc gets shot and killed by Buford Tannen.
    So his death would not impact his younger self in 1955, who has not yet bought a DeLorean, or gone to the Twin Pines Mall, or gone to 2015."
    The upcoming comic book series will show how Marty and Doc met.
    In "Back to the Future II" when Biff steals the DeLorean and goes back in time, gives himself the almanac and in that point he changed the future so this would mean that when he went back to the future to return the time machine, he returned to an alternate 2015 so he shouldn't have been able to return the time machine and thus creating a paradox -- so my question is if you can explain to me what happened there? -- Specter118
    "You're correct, and if you watch the deleted scenes in Part II, you'll see that we originally tried to deal with this.
    Old Biff returns to 2015, staggers out of the DeLorean, clutches his chest...and then he is erased from existence because he was now in a time line in which he didn't exist. But this only makes sense when you see the movie a second time.
    When we previewed the movie for the first audience, they were very confused, and no one understood what was happening. So we decided to cut it before Old Biff disappeared."
    BG: "It seems to me that studios aren't taking as many chances with original material as often as they used to.
    Marketing has become a lot more important than content, but that's partially an outgrowth of the high cost of making a movie and the ease of piracy.
    A movie has to open on thousands of screens worldwide because once it's playing somewhere, someone will pirate it and put it on the internet.
    On the other hand, professional film making tools are now in reach of everyone, and feature films can be shot on phones.
    And the internet has become a distribution channel. So this gives budding filmmakers an opportunity to hone their skills and get their work seen."
    BG: "The book I recommend to every aspiring writer is 'The Art Of Dramatic Writing' by Lajos Egri.
    This was the book from which I learned the craft of dramatic writing, and it was used by many of the best screenwriters of the 1940s and 1950s.
    Be sure to get the unabridged version. It's in the public domain now, and there are some abridged versions floating around that are missing at least half of the book."
    BG: "As Doc Brown said: "30 years. It's a nice round number." The first movie dealt with a 30 year period, so we felt it was appropriate to continue that motif in the sequels.
    Besides, Marty's kids needed to be the same age that Marty was in 1985, and 2015 was the perfect year for that."
    BG: "BTTF has, in my opinion, the perfect cast, so I'll leave that sort of speculation to others."
    Screenwriter Bob Gale wouldn't change a thing about the cast.
    Doc Brown is the stereotypical "absent-minded professor," but I've always wanted to ask if you were really implying that he is actually a bad scientist. That he fumbles and stumbles onto discovery rather than actually being thorough and scientific. Is Doc really just lucky more often than brilliant? -- jape623
    BG: "It was not our intention to imply that Doc was a bad scientist, although he certainly worked on some impractical inventions, notably his brainwave machine. We wanted to convey that Doc is an enthusiastic, free thinker, fascinated by everything, but also very brilliant.
    After all, he invented time travel in 1955 -- but he needed 30 years to figure out an appropriate power source. If Doc had the slightest doubt about the time machine, he wouldn't have put his dog in it, nor would he have stood in its path as it accelerated to 88.
    In fact, Doc had calculated the exact spot that the DeLorean would break the time barrier, which tells us that he knew exactly what he was doing. Similarly, in 1955, Doc is able to calculate pretty accurately when Marty will be erased from existence."
    BG: "Crispin's performance is fantastic, I couldn't agree more. He often had his own way of doing things which was not always what Bob Zemeckis wanted.
    There are some good anecdotes about this in the upcoming book, "Back to the Future: The Ultimate Visual History" and I highly recommend it to all BTTF fans."
    BG: "They were archetypes, with character bits drawn from people we knew, as well as some excellent contributions from actors Michael J. Fox and Tom Wilson."
    BG: "No. I don't think anyone can foresee that sort of thing.
    We were happy that the movie was successful in 1985, and we hoped people would remember it 30 years later, but the fact that it has become a multi-generational touchstone was beyond anything we could have imagined.
    And Bob Zemeckis and I couldn't be happier about that!"
    Who says time travel movies don't make money?
    In "Back to the Future III," in the beginning of the movie Marty takes a picture of Doc's tombstone which mentions a beloved Clara -- how did Clara dedicate him a tombstone if she had fallen into the ravine and died a few days before Dr. Brown's death?" -- Specter118
    BG: "There are three time lines of 1885. In the first, before Doc invented time travel, Clara Clayton's wagon went off Shonash Ravine and she died.
    The ravine was renamed "Clayton Ravine," and that's the history Marty knows. Then Doc Brown invents time travel, accidentally ends up in 1885, rescues Clara and they fall in love. But Buford shoots Doc at the festival and Doc dies two days later, attended to by Clara the entire time. She puts up his tombstone, and that's what they discover at the beginning of Part III.
    In this time line, it's still called Shonash Ravine. In the third version, Doc rescues Clara, they fall in love, Buford is thwarted from shooting Doc by 'Clint Eastwood,' and the events proceed per Part III.
    Everyone assumes that 'Clint' goes over the ravine on the train, and it's renamed Eastwood Ravine in honor of his heroism against Buford."
    Since it was first released on July 3, 1985, "Back to the Future" has become one of the most profitable film trilogies of all time.
    "I live in the Middle East and I was born in the early 90s so I never got to see the movies on the big screen. Seeing them in the theater would be like a dream come true so I wanted to know if the movies would be re-released in this part of the world or globally on the 30th anniversary or any other time." -- Carboman7
    BG: "Seeing Back to the Future with an audience is a wonderful experience, and audiences around the world will have the opportunity to see the movie again in Cinemas in mid-October as part of our 30th Anniversary celebration. In the Middle East, it is likely the film will play in Vox Cinemas.
    Also, we have launched "Back To The Future -- In Concert" this year, in which the movie is accompanied by a full symphony orchestra performing the score, live.
    My thanks to everyone who submitted a question, and best wishes for the future!"