Continuity mistake: When Bender makes the joke about where the professor would be without all the students who love and respect him, we see the professor sitting with nothing in front of him on the table. When it cuts, two glasses and a blue cup suddenly appear. (00:02:35)
Continuity mistake: When we see the professor's clone inside the tube there is a panel attached to a metal post going down to the bottom of the tube. When the professor hits the button to empty the tube of fluid it cuts to a close-up of the clone's feet and the metal post is suddenly gone. (00:08:05)
Continuity mistake: When the clone comes to examine his crew we see Leela being lowered on a platform to the ground. When it cuts to a close-up of the clone the platform, which should be behind him, is gone. (00:08:30)
Continuity mistake: When it cuts to Elzar's restaurant we see, in the wide-shot, Bender cutting his food and liftint the fork with his left hand. When it cuts to a close-up of him he has his right hand lifted. (00:10:45)
Continuity mistake: When Professor Farnsworth places the envelope containing his holo-message on the table, we get a quick glimpse of the front of the envelope, and it is blank, without any writing on it. He then walks away with the Sunset Squad robot, without taking time to address the envelope. When the crew finds the message, the words "For my crew" appear on the envelope.
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]