Sure, the Back to the Future franchise is entertaining. Audiences love to watch Marty McFly, Doc Brown and others experience how a souped-up Delorean can take them to a future with hoverboards, biometric technology, and drones. However, while it is entertaining to watch how the film views the future not all of its elements are possible. We’ve taken a look at a few of them and explained how some can come true and others just aren’t a possibility so far.

Got it right: Biometric technology, video chat and more

As proven by time, Back to the Future got a lot of things right. Platforms like Skype, Facetime, WhatsApp, and others allow us to use video regularly for business and personal reasons. Biometric technologies, like the fingerprint access that Marty’s future wife uses to open her house, has also become a part of daily life, particularly with smartphones.

Another prediction of the film is that USA Today would continue to serve as a prime news source, which it has. The film also features wearable technology, though it looks different in the film than today’s reality of fitness watches and smart clothing. Lastly, the film also correctly predicted the advent of personal drone use which is widely used by consumers today.

Maybe got it right: Time travel

Since the movie’s success, lots of fans question time travel and how Marty can travel through time without creating changes in the past that affect the future and make his time travel less possible. It’s a complicated subject and the best way to start examining it is to look at the portrayal of time travel itself.

Experts appear to have varying opinions on how viable the movie’s portrayal of time travel is. If it is possible, according to physicist Michio Kaku, it would require the capability of jumping time streams. Each time you jump a timestream, which the extreme speed of the DeLorean made possible, and when you go backward in a timestream, an alternate reality is created. Kaku believes that the films show this possibility with relative accuracy.

The use of multiple timestreams helps to explain how Marty and others can do things that change the past without affecting the time they came from. Put simply: the changes they make affect a different timestream than the one that is part of the character’s time of origin. Some scientists have questions about this, including Caltech physicist Sean Carroll. He questions how the multiple timestreams talk to each other and also shows that Marty’s disappearing limbs appear to indicate that past timestreams can and so affect the future in the film.

In the end, it may be good to remember that Back to the Future is a film, entertainment as much as reality. While time travel possibilities are questionable, trying to understand if they can work has its own benefit. Its a great inspiration for fans to learn more and begin to try to understand the real facts of the physics of time travel itself.

Got it wrong: Hoverboards and self-tying shoes

One thing that the film hasn’t gotten right, at least not so far, is hoverboards. However, fans are itching for them and companies are working to get them right. Hands-free wheeled boards are generally available. Though they don’t float on air, the name “hoverboard” has only encouraged sales. Most prominently, Lexus has made a close attempt at a hoverboard but it still doesn’t completely fit the requirements that make it like the device from the movie. Lexus’ version has to be run on a special track and is said to bottom out frequently. So, while the device is closer to the movie than anything else, it’s still not there…yet. Let’s hope that changes in the future.