The scene where Gromit takes the bullet meant for the cornered Were-Rabbit Wallace. Victor loads the Golden Carrot into the gun and fires, blasting himself backwards. Were-Rabbit Wallace cringes away. Gromit's ears shoot up in alarm. Then his eyebrows lower in a determined squint. He speeds towards the scene, swings into the path of the bullet with a rope from a flagpole, and takes it right in the side of the airplane.
Following this, when Gromit accidentally lets go of the rope he's holding, Gromit's plane starts to fall out of the air, leading Wallace to jump out and break its fall, seemingly pulling a Heroic Sacrifice.
Lady Tottington's final scene with Victor. "Consider yourself dumped."
Wallace tossing Victor several yards onto his truck at the beginning of his transformation. Nick Park admitted that this was his favorite scene because it gave Wallace an excuse to be violent.
Hutch rescuing Gromit from the cage he's trapped in.
On that note, the fact that for some fans of Hutch, that he's playable in the video game adaptation.