Continuity mistake: During the vault chase scene, the vault spins on two separate occasions, tangling the lines in the process. The first time, it is being dragged out of the police station and the second when it destroys half a bank. The lines could not have been untangled, because both times they guys were turning to the right and the vault spins in the same direction.
Other mistake: Throughout the entire chase scene at the end, the vault creates sparks on the road. Yet when they get to the bridge, no sparks appear. This cannot be due to the vault being empty at this point, as the vault itself is 10 tonnes, as mentioned earlier in the film.
Continuity mistake: As the cars are being stolen from the train car, they're violently dropped onto the ground, yet they don't have a scratch on them. The best example is the vintage Corvette that Vin Diesel drives out of the train car. The car falls at least 6 feet, landing on the front left corner of the bumper, yet seconds later, the car is in perfect condition.
Continuity mistake: The hole in the plastic which is around the vault Han ordered changes after Tej says "You got a 100 million dollars in a safe, are you going to put somebody else's handprint on it?" This is easiest to spot around the palm scanner: at first, it is completely free, but after that line, the plastic suddenly hangs in front of it.
Continuity mistake: When O'Connor blocks the bus on the two-lane highway with his vehicle, the bus swerves around his car towards the shoulder, clips the right rear of the car, and breaks the vehicle's rear window. In the next shot, the bus reverses angles, flips over the left rear of O'Connor's car nearest the center line, becomes airborne, and then rolls over and over down the center of the highway. If it had continued on its initial trajectory, it would have crushed his vehicle and continued onto the shoulder.
Revealing mistake: Reyes shuts the safe after putting a price on Brian and Dom's heads. We see him close the safe from a camera angle inside the safe. When the safe is shut there is a light reflected on the inside of the door that can't be coming from anything that's known to be in the safe - must be the camera or similar.