The Devil's Hands Are Idle Playthings - S5-E16
Easter egg: On the last disc of the last season, go to the episode "The Devil's Hands Are Idle Playthings". With "play episode" highlighted, click the up arrow on your remote. The Devil's hands will appear. Click enter. You will hear audio of the table reading (rehearsal) of the episode.
Spanish Fry - S5-E12
Easter egg: In the Australian release DVD insert the fourth disk of season five (production series four) and select 'Spanish Fry'. Highlight 'scene selection' and press the left arrow on your DVD remote. The TV screen showing Elzar will change to the icon which is at the start of 'The Devil's Hands Are Idle Play Things'. Push enter to see another list of subtitles that were never used in the show.
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]