The following contains spoilers for F9.
If you're anything like me (I'm sorry), you probably spend large portions of your time during Fast & Furious movies thinking, "Hang on, that's not how physics works." With movies, especially big action blockbusters, we're accustomed to seeing stories take a bit of license with reality. Vin Diesel's car stunt franchise is certainly no exception. In fact, it may be one of the more blatant offenders. Now even an astrophysicist has felt a need to speak up on one of the new movies big stunt sequences, and how the world just doesn't work that way.
California Academy of Sciences astrophysicist Aaron White spoke with IGN and, perhaps unsurprisingly, he had more than a few issues with the F9 handles it's stunts from a science perspective. Most of his focus is on the big finale sequence in the film, where Vin Diesel and his team have all their cars outfitted with electromagnets. White points out that the magnets in the movie are a bit selective in what they pull in, and that magnetic fields are spherical, so they would pull in things from all directions. However, White's biggest issue comes when the magnets start to repel objects away, because magnets simply don't do that. White explains,
There's no practical way to repel iron, or steel probably in this case with those trucks, with a magnet. There are some metals that exist that do have a repulsive property. They're a little more complicated, they're called diamagnets, and in the right conditions you can actually see a repulsive interaction going on there where you can be pushed away from magnetic fields. However, that depends on what the structure of the metal is. So unless Vin Diesel here is an alchemist and he can magically change the structure of these trucks just through the force of his will, I don't think he could possibly do this.
We see the magnets that Vin Diesel and team are using pull cars across roads and while there is sometimes collateral damage where other things get pulled in as well, the movie is a bit inconsistent in how that works. However, Vin's magnet can also then throw the things it has attracted back across the road at high speed. It's an awesome thing to watch on screen, but it doesn't really work out.
Even if we accept that these magnets have the ability to be directed so acutely that they don't pull in literally everything around them. At least attraction is something that magnets actually do, so F9 can be given some space to play. However, throwing the magnets into "reverse" is just not something that magnets are capable of. At best you could turn the magnetic field off and simply drop everything that had been attracted.
Does it matter that F9 just makes up how magnets work? Not at all, but I think it is still useful to know the truth. You can still have all the fun in the world with the Fast & Furious franchise, or any other movie that takes liberties with reality, knowing that things don't really work that way doesn't hamper the movie experience.