In case three "Turnabout Serenade", on day 2 in the Wright Anything Agency if you examine the top hat, Apollo will say "That's one of those hats you pull things out of, right?". Trucy will then say "Of course! My hat's like a little universe! Bigger on the inside than on the outside!" which Apollo will reply saying "Hmm... That reminds me of a sci-fi show I used to watch."

This is a reference to the science fiction series Doctor Who and the spaceship the TARDIS which is bigger on the inside than on the outside.