Tom and Jerry: The Movie/WMG

Tom and Jerry are actors who somehow wandered into the wrong movie.
Okay, let's go with the basic Animated Actor concept used in such things as Who Framed Roger Rabbit and a number of Warner Bros. cartoons and films. Tom and Jerry are, at the start of the film, shooting a new short when all of a sudden the director, writer, and the rest of the crew just walk off the set. (the director is probably yelling at the writer "Okay, where's the rest of the script?!? What do you MEAN you don't know what happens after the house gets demolished?").

Not knowing what to do, Tom and Jerry wander around the various sets of the studio, improvising silently, until they run into Pugsley. At this point, they realize they've walked into a different movie all of a sudden, so they humor Pugsley. They break character by talking and then singing with Pugsley about friendship. Afterwards, they attempt to find their way back to the set of the film they should be making, only to end up on the set of yet another film ... a film about singing cat gangs.

Clearly spooked by this, they decide they were better off in the first wrong movie and rush back to that set, and meet Robyn. The director of that film says "Perfect! They're just who we need to play the sidekicks in this movie!" and casts them right away. Tom and Jerry accept, tired of being typecast and wanting to stretch themselves as actors.

At the film's end at Robyn's house, Tom and Jerry do a chase out of force of habit, and the director decides to just Throw It In because it's a good nod to their normal stuff. And then he finds the unfinished short Tom and Jerry were filming before and slaps it on to the beginning of the movie, and tada! He's got Tom and Jerry The Movie.
 * This is my new headcanon, and the only way I can bear this movie.

Tom and Jerry died during house demolition.
Everything from this point was just their Dying Dream as they lay buried under tons of rubble, a nightmare world in which they talk and are friends and their roles are reduced to sidekicks of a little girl, sort of a metaphor of the franchise dying with them...
 * And, when they finally chase each other, they're trying to hold on to their last shreds of their previous forms before finally slipping into oblivion...

Tom and Jerry could always talk.
They're just so preoccupied with the chase that neither of them really bother speaking, except for those brief moments in the original shorts. Also, despite what fiction might tell you, high speed chases don't really leave a lot of time for witty banter.


 * This is pretty well supported by the original shorts too.
 * I'm pretty sure that's pretty much exactly what they said in the movie

Willie Scott was Robyn's moher
Both are blonde, both were completly unecessary additons that ruined the film of a beloved icon, and she did date Indianna Jones. The dark truth is that Willie and Indie broke up shortly after The Temple of Doom, but not before he unknowingly got her pregnant. Being the screamy, shallow whiner she is, Willie dumped Robyn in an orphanage. However, she had just enough human decency to give her a locket of her father, allowing her to locate him if she ever got into trouble.

The movie is a Stable Time Loop
Both Robyn and Tom's owner at the start of the movie are blonde. Tom and Jerry get amnesia from the wrecking ball during the demolition of the house. This allows Time Lords Pugsy and Frankie to send them back in time using what appears to be a Model T on cement blocks without them noticing. Off-screen experimentation by "Doctor" Applecheek gives Tom and Jerry the immortality needed to complete the time loop. As seen at the end of the movie Tom and Jerry's destructive ways have eaten through Robyn's inheritance and forced her to sell "Robyn's nest" and move to the suburbs by the time the start of the movie happens again.