Star Wars Episode 1: The Phantom Menace - Darth Maul Gives Qui-Gon the Finger, and Anakin Must've Been Swearing Too, Because His Lip-Sincing Is Horrible!
In the begining of the deserth battle sequence, we see a shot where Anakin is saying, "Qui-Gon Sir, Wait, I'm Tired!" If you look at his mouth, the voice was obviously dubbed. As if things couldn't get any worse than that, freeze frame the shot where Darth Maul does a super-flip off of his speeder. If you look real,real,real,real closely, Maul's Giving Qui-Gon the FINGER!!! This has been confirmed. Want any more bloopers from this scene? Okay: When Darth Maul's zooming up behind Anakin, then flies over him, his cloak is obviously super-tight to stop it from blowing violently around. Compare that look with his descent down the canyon and the lightsaber battle. They must've been blowing fans at the guy who played Maul, Ray Park.
Really good eyes, the movie (more preferably the full-frame version), and a sense of humor.