Riff Trax/WMG

Rifftrax is a true sequel to Mystery Science Theater 3000.
The final episode of MST3k sees Mike and the Bots escape to Earth and, for lack of anything better to do... start watching a bad movie. RiffTrax reveals that, years later, they're still at it; old habits die hard, after all, and if they're going to keep watching terrible movies, they might as well get some monetary benefit from it, eh? Of course, to avoid unwanted attention, the Bots have to hide the fact that they're robots -- hence Tom Servo masquerading as Kevin Murphy and Crow pretending to be Bill Corbett.
 * Life is now worth living, thanks to you.
 * They're using Pretender shells to appear human, so they riff on the Transformers films to distract from it.

All the jokes are canon.
Every line that is said in character and every obscure factoid that is mentioned is canon but was cut from the final movies due to isues regarding pacing, sake of drama, etc.

Malachai and Ethan Nicolle will guest riff a movie.
Ethan has already done art for a Rifftrax iPad giveaway, and Axe Cop was referenced in the Clash of the Titans riff. No doubt the brothers will guest in a Rifftrax, probably one riffing a superhero movie.
 * X-Men 3 has been curiously ignored, though I'm not sure Ethan would let Malachai watch something like that. It is pretty racy for a superhero movie

The last riff on the last Twilight movie will be...
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..."Line?"

Reggie from the "Beginning Responsibility" short grew up and became Dan from the "Basic Job Skills: Handling Daily Problems" short.
He became so ashamed of his past behavior that he changed his name, although he kept the same personality.

Disembaudio is the son of Magic Voice and Cambot
After the cast became pure energy at the end of Laserblast, Cambot and Magic Voice (finally being able to physically interact) began an affair. Magic Voice and their child stayed behind when the rest of the crew returned to the S.O.L. Not to worry, they reunited when the S.O.L. returned to Earth.

There will be a Bone-Saw joke in The Dark Knight Rises riff
Come on. You'll all see it coming.