At the end of the episode Walter says Sly is in the bunker and is going crazy. The scene changes to show Sly in the bunker talking to a lizard and eventually starts to sing. He starts singing "Daisy". This is humourous because he is arguably the computer of the group and its the same song HAL sings once it's determined that HAL is crazy and Dave is deactivating HAL in 2001 A Space Odyssey.