This miniseries went through many, many changes during development.
Who Killed Markiplier?
- The original idea was that the Jims were going to be the perpetrators of Mark's death, doing so in order to get a good story out of the events.
- It was originally meant to be like Clue, but with Marks alter egos. They scrapped this idea on account of it being too cumbersome to do, along with putting too much pressure on Mark to play multiple characters at the same time.
- It was planned for Abe to have a Hook Hand that would let him attach and detach other tools, such as a magnifying glass.
- Ethan was supposed to play a maid character, but was unable to do so because he had to be the camera person along with Amy
- The Party scene was to be much more involved, but the crew didn't have enough people to use for the scene. It was then discussed that Amy and Kathryn could have acted as extra guests, but then they would have had to disappear after that, which would have required writing their disappearance into the story, so that idea was ultimately scrapped.
- While Mark intended for Damien and Celine to be brother and sister in the script, he ultimately chose to leave their relationship up to interpretation. Mark also considered making William and Actor Mark brothers before deciding that they just grew up in the same house. Damien and Celine were eventually revealed to be Brother and Sister in the side story, "DAMIEN".
- The crew was supposed to film a scene in the basement where the Russian Roulette between the Colonel and Markiplier took place, but they forgot to include it in the final product.
- The original idea for the ending was that Darkiplier was going to be Damien in Mark's broken body rather than being Damien, Celine and the D/A merged into one being. William's fall to insanity also wasn't originally planned to be shown in the ending either, but Mark wrote it in because he felt the story needed that final Gut Punch.
- The episode was originally planned to be about 30 minutes long, but Mark cut down the script in order to keep the story from dragging on too long and lower the cost in terms of animation. Notably, the loops were cut down from three to two.
- The ending was originally going to be much shorter, but Mark felt that it wouldn't have given Damien a choice in what happened to him after being dragged around by everyone else throughout the series, which had always been a major part of his character, so he changed it to allow Damien to make the choice of helping Celine.
- The Stinger was originally going to have Wilford find Damien at the cabin, asking about Celine, with "Damien" replying that she's asleep. Wilford would've then told him about his great idea to make a TV show, with a long pause before Dark agreed to it, leading directly into "Markiplier TV". While this alternate ending itself isn't canon, "Markiplier TV" immediately following "DAMIEN" is confirmed to be canon.