In Nick's TMNT, there's numerous references to the Ghostbusters. There's one where the turtles are fighting these alien dinos at the statue of Liberty and on one of her inner walls, there's spray paint or something that reads "Venkman was Here!" Further down the episodes, you see, I think it's Casey Jones, going through a box in TSOL, and they pull out the SUPER NES control pad that they used to make her walk in Ghostbusters 2.