Visible crew/equipment: When Zaphod says his first line "I certainly didn't survive.", you can see the person who plays his third arm standing behind him.
It's Only Rock and Roll - S3-E11
Visible crew/equipment: After Ralph walks into his house with Bill and Dak, when Bill explains to Pam that Dak will be spending the night, the T-mark is visible on the floor in front of Bill. (00:31:05)