Factual error: During the first tunnel sequence, all the cars travel very far into the mountains, turn lots of corners, yet not only is Gisele still able to speak to them over the radios, their GPS still works. GPS signals invariably need a clear 'sight' of the sky and can penetrate light cover, but most certainly not that depth and cover.
Continuity mistake: When Dom slams his black Buick Grand National into the side of the Petroleum tanker to get the coupling to break, the entire side of the car is stoved in, and the rear axle is seriously bent as evidenced by the angle of the back wheel. All subsequent shots, however, show the wheel intact and the damage to the side as slight denting.
Visible crew/equipment: When Brian at the end says "don't make me laugh", if you look at the chrome bumper of the green Torino he's leaning on, you can see a member of the crew moving. It's not Toretto as he's on the other side of Brian, and it's not any of the Police as evidenced by the following shot that still shows them to be far away.
Continuity mistake: The tractor trailer rams the rear of the Buick twice. Just before the second impact, we can see the rear bumper of the Buick is hanging well below its normal location and the sides of the car show crumpled damage. Moments later, the car spins around alongside the trailer and the rear of the car is undamaged.
Factual error: During the final chase across the desert, Dom fires at several cars, shooting out their tyres, several of those cars then stop dead and the back ends of the those cars lift up and flip over. Those cars might lose control, but it wouldn't cause the back ends of the cars to defy gravity in such a way unless they actually hit something, which they never do.
Continuity mistake: Moments before Letty leaps off the trailer onto the hood of the Buick, a quick shot (just as Dom begins to say "You gotta jump!") shows the hood is already damaged from a previous attempt of this same stunt, despite all the preceding shots showing no such damage.
Factual error: Dom removes the hose from his nitrous oxide cylinder to fill his car with the gas and then pushes in his cigarette lighter. The fact is that nitrous oxide is not actually flammable on its own. Nitrous oxide is an oxidiser that contains a higher oxygen content than air. This is why it is pumped into engines so that more fuel can also be added to create a stronger explosion. Filling a car with nitrous oxide would not make it explode. You could put a lighter in the car surrounded by the gas and it just mean that the flame would burn brighter - not create an explosion radius of about 5 metres. It is not explosive when introduced to heat. The only way this is true is if the bottle itself was heated up to explosion levels - would be a few hundred degrees as they are pressure tested to significant levels.
Plot hole: Throughout the first half of the movie the focus is to locate and find David Park. It is believed this will lead them to Bragga and they can arrest him. However, later in the movie it is revealed that Letty was working with the FBI and was killed running drugs for Bragga. This means that the whole storyline to find Park was useless because they already knew how to get people inside.
Factual error: There's no way the pickup trucks could haul the stolen tanker trailers, even as modified as the pickup trucks are. The gas engines they are using don't have the necessary torque to haul the probably 30,000 pounds the full trailers weigh, and the trucks do not show a heavy enough suspension to haul the weight either. Besides, no one hooks up the airlines necessary to release the trailer brakes.
Factual error: During the first theft of the tankers, the pickups backing up to the tanks throw an A-frame over the pintle hitches to steal the trailers. Aside from the fact that it is extremely difficult to hook up that type of hitch, even when stationary, there is a closure over the hook that locks the eye of the A frame in place to prevent it from popping out of the hook. It would be impossible to throw the eye over the hook on a normal hitch that way, and the close up shots of the hitch show the top closure missing. If it's missing, the eye would pop out of the hook either braking, hitting a bump or accelerating.
Revealing mistake: Just after the Buick spins around to knock the trailer loose, we see the Buick speeding away backwards alongside the truck. If you look carefully you can see the REAR tires are steering, not the fronts. This car was modified with the body mounted backwards on the chassis because the transmission only has one reverse gear, so to get the speed and handling needed, the car had to be going 'forward' with a 'backward' body.
Continuity mistake: When Dom steers into the path of the tractor-trailer to slow it down, the actual swerving of the Buick occurs immediately in front of the tractor, just a few feet ahead of it. As the Buick stops wiggling in the next shot, we can see the tractor is far behind the Buick instantly.
Factual error: When Dom emerges from the tunnel driving F-Bomb, he downshifts and presumably hits the throttle, causing the car's front end to lift. The car is on dirt and wearing street tires. It's not physically possible for the car to get the traction required to transfer whatever amount of horsepower we're expected to believe the car has to the ground, so that the front will lift. The only reaction the car would have had was to spin the rear tires wildly, kicking up more dirt and likely causing the car to swerve 'furiously'.
Revealing mistake: When Dom and Letty get out the car at the crash scene, there is a light reflected in the paintwork quite low. When the camera pans out you can see it's not the moon due to its position, and there is no other light source around that could cause the light to be reflected so low on the car.