Continuity mistake: Rumplestiltskin looks completely different in this movie than he did in the previous film Shrek The Third; Prince Charming momentarily talks to Rumplestiltskin in the tavern during the third film, and the character looks completely different, has a different voice and different demeanor.
Continuity mistake: In the scene where Shrek goes back to the swamp after signing the contract, he realizes that Fiona isn't there and pulls out the contract to read it. He then notices something flying overhead and looks up to see the witches. In the next shot, we see no contract in Shrek's open hands. (00:22:30)
Continuity mistake: In the scene when Pinocchio arrives to request Rumpelstiltskin to convert him into a real kid there's nothing on the table but goblets and kind of cakes, after Rumpelstiltskin asks to the wolf his wig, he suddenly takes the contract from the table and on it appears the feather and ink that Pinocchio uses to sign the contract.
Continuity mistake: It was morning when Shrek enters the castle, because Donkey shouted to Shrek, "and find us some breakfast." And after leaving the castle, Donkey found a waffle and got pulled toward the ogres' hiding place. Once inside the hiding place, Shrek tried to take Donkey away from becoming a "dinner" by saying "Your dinner is my friend." Immediately Fiona showed up as an ogre, which confirms that it has suddenly become night. (00:36:30 - 00:41:05)