Some TMNT stuff really isn't for little kids.
Along with his fellow Turtle Ghostbusters, Bill mistook Peter Venkman for some kind of supernatural entity menacing Michelangelo. When Venkman was captured, Dan attempted to reassure Michelangelo before heading back to their home base.
When Michelangelo was caught attempting to free Venkman, Dan was the one who attempted to reason with the entity he believed was possessing the young Turtle. He was shocked when Michelangelo directed the Turtle Ghostbusters to check Venkman's proton pack, and came to the conclusion that the pair were probably telling the truth. However, he still wanted to scan them first.
Afterwards, he expressed embarrassment over the mistake, though clarifying that Venkman resembled a demon impersonating someone, and witnessed Venkman and Michelangelo leaving their dimension.
- Dan is named after Dan Aykroyd, who portrayed Ray Stantz in the first two Ghostbusters films, as well as Frank Welker, who voices the same character in The Real Ghostbusters. Peter Venkman makes a reference to this being this dimension's version of Ray.