This episode is one of my favourites starting with the 20th century "Pastorama" with Fry explaining that the phone booths weren't suicide booths but were used for bathrooms.
Another Bending unit, Flexo, appears in this episode and is a great character in that he's always joking in a serious voice.
The fact that the audience thought Bender was Flexo because he acts suspicious and is always covering his chin (where flexo's beard is). The end with Zapp Brannigan and the revelation that Bender took the tiara meaning "Bender is the evil bender? I am shocked ! Shocked! well, not that shocked."
My favourite scenes are when Fry is looking for Flexo in Leela's underpants drawer because "he wasn't here ten minutes ago so I thought I'd check again", when Farnsworth is discussing the tiara with the crew while he's in his bed, then bath and when Fry realises that the Bender he likes turned out to be evil. Great moral: Never trust anybody.