All of the connections to part one are shoehorned in, not just the exorcism. The others are Blatty’s fault, not the producers’, even the presence of Father Karras. He could have made a standalone story about the Gemini instead. The change the studio made was to cast the original actor as Karras instead of Brad Dourif. The change actually makes sense. Why cast a different actor when the original guy was still alive? George C. Scott replaced another actor only because the original guy died. (Jason Miller was originally unavailable, then became available after Blatty’s first cut. Maybe they should have waited for the original actor to begin with.) I agree flipping back and forth between Dourif and Miller probably wasn’t the best idea, but I can also understand not wanting to cut Brad Dourif out entirely when he’s a much better villain and they already spent so much money on his scenes. Also, they probably should have avoided the demonic makeup on Jason Miller since it makes him less recognizable and most of the time he’s not possessed by a demon. The Gemini was just a person. The exorcism was an improvement over the original ending. It’s an anticlimax if Kinderman just walks up and shoots him.