Back to the Future is chock full of futuristic ideas but there was one that screenwriter Bob Gale was not able to imagine back in 1989: smartphones.

To Gale, smartphones are like the Swiss army knives of today, just a singular device that can function as a computer, a camera, a recording device, a calculator and even as a flashlight. "We didn't think that," he said in an interview with The Hollywood Reporter, talking about the kind of future that he and Robert Zemeckis dreamed up for Marty McFly, who, according to Back to the Future Part II, will be arriving on Oct. 21.

Many of the ideas Gale and Zemeckis came up with for the movie were the result of the two just goofing around. However, some of the inventions that were just in their heads back then are actually seeing reality today, if not in the not-too-distant future.

"We weren't seriously thinking about how that technology would work, but wow," he said, referring to drones being capable of taking news pictures. Gale added that drones may not be walking dogs yet but that's bound to happen sooner or later.

Overall, he's happy his work in Back to the Future has inspired reality but he admitted that he's still mostly shocked that their gag inventions are seeing utilization today. Gale wishes, however, that fusion energy already existed so the world will have a limitless source of highly affordable energy. He doesn't think it's going to happen but, if it did, it would definitely solve a lot of problems.

Christopher Lloyd and Michael J. Fox were also joys to work with, Gale shared, never balking at any of the futuristic ideas he and Zemeckis threw at them during the production. Maybe it's because everyone understood that they were having fun with what they were doing. After all, Gale and Zemeckis didn't set out to seriously predict what like would be like in 2015.

But now that 2015 is here, Gale is starting to think about what technology will be like in the next 30 years.

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