When Will pulls the whip back, he cuts Amy's face. When she runs up to him, the cut is gone.
When Hancock sits up, he has a bottle in his hand that he didn't have seconds earlier.
(at around 1 min) You can see Devin Crittenden wearing a pair of yellow shorts with his legs shown. After Crista Flanagan hit him with a guitar, it was obvious that they used a double, because the legs don't match.
In one shot, the Enchanted Princess is holding the shoe-phone. The shot switches to the other people. When it switches back, the phone is gone. Later, Calvin is wearing it, without retrieving it.
Calvin gets out of the Mach 5 1/2 and starts running towards the front of the car, but when the Enchanted Princess gets out of the car, he's behind her when she runs away.
The "naked" Incredible Hulk is clearly wearing green-colored underwear.
The website on Amy Winehouse's I-Book is 'FaceNook', but it is called 'FaceBook' in the dialogue.
When the Princess is shooting Speed Racer over and over, the slide on her automatic pistol never moves, plus no spent casings are ever ejected.
The sword on the statue that Amy is pinned under has a wide blunt tip that's obviously resting on her shoulder. She's not "pinned through to the floor" like Will says.
Juney sings "I just sold the baby to the highest bidder on eBay," but the website she's on is called "Upay" not eBay.
During the end dating song, Batman's guitar starts playing before the shot switches over to Batman.
If the Crystal Skull is not placed on the altar, the entire world will end. With this in mind, Beowulf and Kung Fu Panda have no motivation for wanting to stop the main characters.