[m_maxwell]

This may or may not count as a blooper. In Harry Potter and the Sorceror's Stone, after Quirrel yells "Troll in the castle!" and faints, all the kids panic and run away. Quirrel moves a bit as some of the kids pass him. Considering that the character had only been pretending to faint anyway, this might not be much of a blooper.
In one of the Batman movies (forget which one) Alfred gets knocked out by the Riddler (I think) and moves a tray out of the walkway- while he's supposed to be knocked out.
Disney bloopers!
Lots of recent Disney films have characters from other films making cameo roles. Look for:
Scar in Hercules
Mrs. Potts and Chip in Tarzan
Belle in The Hunchback of Notre Dame
The Beast in Aladdin
Mickey and Donald in The Little Mermaid
Mulan: In the "Reflection" number, Mulan wipes her make-up off on her sleeves. But later, there are no stains on her dress.
The Rescuers: In one frame (you will need a DVD to catch it) during the scene where Bianca and Bernard are flying on the albatross, there's a naked woman in one of the windows in the background.
The Little Mermaid: In some scenes, Ariel has blue eyes. In others, they're green.
Oh, and the "All good kids take off your clothes." line from Aladdin is just a rumor. What he's really saying is "Good kitty, take off now."