Jack asks Liz to wear a "Sheinhardt Wig Company" shirt to show support for a parent company who is having a PR hiccup. Seconds later Kenneth walks in and you can see he is already wearing a shirt under his page jacket as well.
Frank's trucker hat reads "Karate Prom".
When Jonathon is hanging up Jack's suit in with all the other identical suits in the closet hidden behind the fake wall, the incidental music is from the refrain from the song by 10cc, "The Things We Do For Love."
Tracy's chain disappears while he's dancing as rerun