I Knew It: This film confirms the fan theory that Tom and Jerry enjoy their game of cat and mouse. Once they're homeless, they get along like a house on fire.
The Other Darrin: Technically the title characters, who previously had a slew of other voice actors the few times they'd been voiced. This was the first (and only) time Richard Kind and Dana Hill voiced Tom and Jerry respectively.
Though the film makes it seem that Tom and Jerry have never talked before the events of the film, in reality many of the early shorts feature Tom and/or Jerry speaking, with Tom speaking much more frequently than Jerry. Of course, this is assuming the shorts take place before the film.