Corrected entry: In the Special Edition, when the first of Jabba's henchmen is thrown into the Sarlacc pit, the Sarlacc has reverted to its original design (without the beak). Then when the next one gets thrown in, the beak has returned. Later on, when it burps after eating Boba Fett, the beak has vanished again.
DaveJB
22nd Oct 2004
Correction: The Sarlacc is probably able to make the beak retract into the pit whenever it wants to.