Revealing mistake: After Mike starts shooting at the KKK meeting he rolls on the ground as he's firing at klansmen, and when it cuts to shots facing those klansmen, the stunt springboard is visible in two consecutive shots. (00:08:30)
Revealing mistake: During the first gun battle, Mike blows up a bridge with two men on it. When they go flying, the man on top is attached to a very visible wire that lifts him up and sends him flying. (00:08:35)
Continuity mistake: In the White Power vs. Blue Power scene, Mike jumps and shoots a bullet in slow motion. While following the bullet, you can see one man take 3 or 4 steps, before the bullet hits Marcus's ass and eventually the guy's neck. (00:09:15)
Continuity mistake: In the "white power vs. blue power" scene when Mike yells "Marcus!", he fires both his Glocks. But in the following slow-motion shot, the bullet from the gun in his left hand is nowhere to be seen, although you can see he fires them in the same direction. In fact it probably would have hit Marcus, while the bullet from Mike's right-hand gun scrapes him in the bottom-cheek. (00:09:35)
Continuity mistake: After Marcus is shot in the butt, Mike shows up with a donut for his behind. When the scene shows Marcus from the front, Mike is holding the doughnut out. When the scene switches to showing Mike from the front, the donut is close to his face. (00:16:40)
Visible crew/equipment: During the scene at Marcus' BBQ you can see a reflection of a light screen in Mike's sunglasses when he puts them on. (00:17:40)
Continuity mistake: When Syd arrives, the dog is swimming around in the pool in Marcus's house. In the next shot, just before the pool collapses, the dog is out of the pool and isn't even wet. (00:18:50)
Continuity mistake: During the shootout in the street, Will Smith does a sharp turn while shooting at the Haitians and ends up killing one Haitian who falls back on a car. A few shots later at a different camera angle, you see the same Haitian man get killed and fall back on the hood of a car. (00:20:00 - 00:31:55)
Continuity mistake: At the start of the long chase scene with the Haitian gangsters, the gangsters are running to their muscle cars to start chasing Syd. The orange muscle car has a noticeable dent/crumple near the right headlight. Later on in the scene, this dent is gone. (00:25:25 - 00:28:15)
Revealing mistake: When Syd and the Haitians are running, there is one shot where skid marks are visible on the road in the exact place the Haitians skid. (00:27:40)
Continuity mistake: When the Haitians have a shootout in the intersection, you see Mike do a 360 degree spin and then shoots the first Haitian in the green, but moments later you see Mike shoot him again. He was already dead. (00:29:15 - 00:30:35)
Revealing mistake: When Mike and Marcus are chasing the Haitians, when Mike does a 360 degree spin and then fires his UMP-45, for a split second when he is spinning if you look into the window, you can notice that the driver isn't really Mike. (00:30:25)
Continuity mistake: In the truck chase, the amount of damage to the front of the truck changes throughout. Keep an eye on the grill two pieces keep disappearing and reappearing. (00:33:10)
Continuity mistake: When the Haitians are on the highway, one of the cars fall off and is dragged by a chain and it hits the large black Ford beside it, with just a bridge wall. Then when the thug (the one who says, "Jesus f***") is shown inside the car, there is a Maersk Sealand vehicle there. (00:33:20)
Continuity mistake: During the chase scene, Marcus and Mike are being shot at. At one point the car headlight is shot out. The headlight is intact for the rest of the scene. (00:33:45 - 00:35:25)
Continuity mistake: During the freeway chase scene, the windscreen of the car first thrown from the top of the truck smashes out at least three times. (00:34:00)
Revealing mistake: When Mike is saying "shoot outside the car" the background outside the car is completely still, despite the fact Mike is still driving at speed. (00:34:10)
Continuity mistake: In the highway sequence, you see a white car being pushed off from the top deck of the trailer, by the Haitians, and in the next shot it manages to land upside down. Also, the Haitians on the top deck of the trailer, are now gone. (00:34:15)
Revealing mistake: In the first big chase scene the bad guys make the cars roll down from the car transport truck to block the street. You can see that there are stunt drivers sitting in some of those cars to keep them under control. (00:34:20)
Continuity mistake: After the first car has been thrown from the top layer of cars on the trasporter, the windscreen of the car thrown off is seen to come out. The camera changes and it's back on the car. The camera changes again, and the windscreen pops out for a second time. (00:34:25)
Answer: He was looking through a tiny mirror he was holding in his hand.