Revealing mistake: Near the end, right when "little wonders" starts, Lewis takes a moment to look at his future family, Lucille, Frannie, etc. When there's a closeup on Lewis, his memory scanner reveals a reflection of no one in the gym, except for Lewis, even though people are supposed to be standing in front of him.
Revealing mistake: When Tess walks into Lex's office, he is standing at his window looking out, or at his reflection. When he turns around and begins typing on a hand held device for the cure to Muscular Dystrophy, he at first only turns half way around, being 90 degrees and now facing parallel to the window. However, his reflection turns around 180 degrees and like he has his back to the window. (00:06:40)
Revealing mistake: After Homer knocks out the guard guarding the dome, Homer runs into the supplies shack. As he walks through the doorway, his right arm passes through it.
Revealing mistake: When the Level 3 Sentry is firing up into the air for no apparent reason, it fires some rockets with a clear defined smoke trail behind them and disappear off screen. Then the shot jump cuts to further away and suddenly the smoke appears again, but the end of the smoke trails are solid and crisp indicating the animators used the smoke animation as if the rockets had just been fired from that spot... in the middle of the sky. (00:01:10)
Revealing mistake: When everyone is cheering to Bender, you can see Fry on the right hand side of the screen wave to him twice. The second time he cheers, his hands move from the table to suddenly waving at Bender without any animation. (01:19:50)
Revealing mistake: Meatwad and Shake get booted off the computer by Frylock so he can find instructions to the Insane-O-Flex. Watch the computer monitor. It rumbles, but the logo on it stays still.