Visible crew/equipment: In the skateboarding scene there is a close up shot of the guy with red pants on. As he skates off the screen you can see a shadow of what looks like the camera man following him. It can't be a shadow of another skateboarder, because they were all skating ahead of the guy in the red pants.
Revealing mistake: In the scene near the end, when the two cops are fighting in the "out of control" bi-plane, the plane is seen looping and twisting as the "pilot" Tack has jumped out. However, in the side-on view of them fighting you can see a new pilot trying desperately to stay out of shot, but failing due to the g-forces he is under while the plane moves around.