Shrek: You know, I always thought I'd rescued you from the Dragon's Keep.
Princess Fiona: You did.
Shrek: No. It was you who rescued me.
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.
The flute solos played by the Pied Piper were played by Jeremy Steig, a well-known jazz flutist. He is also the son of William Steig, the author of the original Shrek books.