Executive Meddling: Averted in the original. Tobe Hooper avoided excessive gore and showed the violence in quick cuts because he was originally aiming for a PG rating(!) The censors were pleased. The other films in the franchise are a different story altogether...
Leatherface: Texas Chainsaw Massacre III was completely destroyed by the censors and the executives.
Jossed: A lot of background stuff introduced in the novelization of the remake is rendered non-canon by The Beginning.
Money, Dear Boy: Michael Bay once stated the he only produced the remake due to the name appeal alone.
Troubled Production: The filming of the original was a miserable experience for all concerned; cast member Edwin Neal memorably stated that shooting some scenes were worse than anything he experienced while serving in the Vietnam War.
Gunnar Hansen was offered the chance to return as Leatherface for the second, third, and fourth films, and he was interested in doing so- but each time, the producers refused to pay him any more than standard union rate, so he consistently turned them down.