Star Trek and Back to the Future
This movie has some neat little ties to both of the franchises mentioned in the title.
Star Trek is mainly casting choices. With Patrick Stewart (Picard) as Adventure, Whoopi Goldberg (Guinan) as Fantasy, Christopher Lloyd (that one Klingon from Search for Spock) as the Librarian/Pagemaster, and Leonard Nimoy (Spock) as Jekyll/Hyde, I'm surprised I haven't encountered more people making this connection.
As for Back to the Future, that mainly derives from one scene in particular. The scene right before Kevin gets to the library features him riding his bike through a tunnel in the rain about to see Christopher Lloyd and he will soon be going to the library. Does that sound familiar? Well, no, because it's not a particularly famous scene. Regardless, that tunnel is the same one where Biff cornered Marty in BTTF II, and Marty was rescued from that situation by Doc (Chris Lloyd, of course) and went to the library the next day (in Part III). The last part wasn't anything important; I just figured I'd add it in because it fit.
"I'm the RA, and as the RA, I'm supposed to be the fun-sucker. I *beep* the sun."
-Abe Christiansen