Pilot
None so far.
The Power
The song that The Power plays is a remix of Tom Sawyer by Rush.
Most parts were removed for the British audience.
Just Set up the Chairs
Contrary to most beliefs, this is the first time High five ghost AND Muscle Man speak.
Caffeinated Concert Tickets
This is the first episode to have a copyrighted song (Hold the Line by Toto) in a scene other than a montage.
*Skips to Dizzy*
Dizzy
Although this was removed from the wiki, the original episode was supposed to be about Mordecai on a Merry-go-round (forgot why. It had something to do with them playing a game) and going so fast Mordecai nearly went blind.
*goes back one episode*
Peeps
This episode was originally going to be called "Trapped in the Closet," conflicting with the next fact.
It was originally going to be about the gang trying to get rid of some baby chicks that think Mordecai is their mother.