Trivia: After co-creator Justin Roiland was fired, it was revealed that his relationship with fellow co-creator Dan Harmon had broken down during season 2 when Harmon pushed for the show to be more ambitious. By season 3, Roiland made little creative input, was rude and inappropriate to the staff, and would often abandon work. By season 4, he would just record his lines from home and never come into work, exploiting the fact he was voicing the leads because he thought it meant he could never be fired.
Trivia: The show originated as a 2006 short parody of the film series "Back to the Future", entitled "The Real Animated Adventures of Doc and Mharti." Eventually, creators Justin Roiland and Dan Harmon reworked the concept into the series that would become "Rick and Morty" during the brief time that Harmon was fired from his other series "Community" during the fourth season. When Harmon was rehired for the fifth and sixth seasons of that show, he simultaneously worked on both series at the same time.
Answer: C-137 is the dimension they came from since the pilot. After C-137 is Chronenberg'd, Rick and Morty travel to a replacement dimension that we haven't found out the designation of (although they may have moved dimensions again). The "original" Jerry, Beth, and Summer are still on C-137 though.
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