A Big Piece of Garbage - S1-E8
Continuity mistake: In the scene where Leela is telling Fry how even his food is recycled (just after they have seen the video of the origin of the garbage-ball) you can see both Fry's drink can and sandwich on the table. After the closeup of Fry his sandwich has disappeared but in the next full-table shot it's back (albeit moved to Fry's right along with his drink can). (00:10:00)
A Big Piece of Garbage - S1-E8
Continuity mistake: Most of the objects on the Mayor's desk disappear (e.g. the photograph, the lamp) when Professor Farnsworth starts to write his plan on it. (00:17:10)
A Big Piece of Garbage - S1-E8
Continuity mistake: When the team first meet the Mayor, the writing on the Mayor's nameplate disappears after it is first seen, and the button on his desk that he pushes wasn't there before. (00:10:35)
A Big Piece of Garbage - S1-E8
Continuity mistake: When the Death Clock is put on the table, the readout panel is facing away from the edge of the table. In the next shot, it is facing Leela and the edge of the table. (00:00:35)
A Big Piece of Garbage - S1-E8
Continuity mistake: The dagger and sheath on the boot of Leela's space boot only appears when she needed to cut off the elastic caught around his neck, and then disappears directly afterward. (00:14:10)
A Big Piece of Garbage - S1-E8
Continuity mistake: The FunkOMeter doesn't appear on the telescope until Professor Farnsworth points it out, and it disappears again afterwards. (00:07:15)
A Big Piece of Garbage - S1-E8
Continuity mistake: When Bender is ordering from the wine list, the waiter's notepad changes colour from yellow to white. (00:02:40)
Answer: You are thinking about episode 20 of series 2 - "Anthology of Interest I". She technically never kills anyone, but in the episode she ask a "What if machine" (one of the Professor's inventions) what would happen if she was more impulsive. The machine then shows the more impulsive Leela killing off the Professor to get the money from his will and thereafter killing Hermes, Bender, Scruffy, Cubert, Nibler, Amy and Zoidberg to cover it up. Finally she does something really impulsive with Fry.
Andreas[DK]