Continuity mistake: When Fry tells Bender he now can pay off the loan sharks, Fry has his hand on the bowl of cereals in front of him. When it cuts his hand is off it. (00:07:15)
Continuity mistake: When Bender lies on the roulette the numbers keep changing between the shots. For example when Bender's antenna lands on the number "21", the number beside it is "25". When it cuts the number "25" has suddenly changed to "4" (00:07:50)
Continuity mistake: When Bender and Fry is hanging on to Leela while she is climbing the Watergate building, the width of the concrete on the wall is about 3 feet. When it cuts the width is reduced to no more than about 1 foot. (00:16:50)
Continuity mistake: The crack on the balcony suddenly appears once Bender yells at the people in the room. (00:17:40)
Continuity mistake: When Bender plays the recording of Nixon his body is sitting right behind him. As Leela takes the audio tape out of Bender's mouth his body is gone. (00:19:10)
Continuity mistake: When they first show Richard Nixon on the couch by Bender there is a huge scratch in the wall, but in the next shot they show him it isn't there.
Revealing mistake: In the scene near the beginning where Leela tells Fry and Bender to watch the political debate on television, both of them (Fry and Bender) fall asleep. When Leela "hops" on the couch to wake them up, Bender's arm, despite being behind Leela, can be seen through her white shirt for a few frames.
Continuity mistake: In the Hall of Presidents, Bill Clinton's head is above Jesse Ventura and Jimmy Carter. When he starts to hit on Leela, he's now sitting above Gerald Ford. Later he shifts again, being above Carter and Ford.
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]