Revealing mistake: About seven minutes in, during the scene where we see Cooper helping the Nerd as a cameraman, you can tell that Cooper has been added to the scene using green-screen effects, as the actor was unavailable to shoot at the location. The lighting on Cooper doesn't quite match the lighting of the scene, and you can see a slight "blur/feathering effect" around him where the greenscreen background was removed.
Angry Video Game Nerd: The Movie (2014)
1 revealing mistake - chronological order
Directed by: James D. Rolfe, James Rolfe, Kevin Finn
Starring: Jeremy Suarez, Bobby Reed, James D. Rolfe, James Rolfe, Sarah Glendening
Continuity mistake: During the climax, when the old-fashioned Atari-controller is lowered down from the UFO, watch closely. In the first two shots, it's swinging back and forth rather quickly and dramatically, however, immediately from the third shot on, it's suddenly barely swinging. It's too instantaneous between edits to be the result of it naturally losing momentum.
The Angry Video Game Nerd: Cooper. If you want to be a nerd like me, you gotta make some unique sacrifices. No physical fitness, no social popularity and most important, no girls.