During the scene with Marshall trying to kill Abe on the Tinseltown Starliner, when Homer is getting lowered by Lenny and Carl, there's a shot where they're both showed. In that shot, Lenny doesn't have his signature stubble beard. In the next shot in which they're shown, it's back.
"When I rode with Abe Simpson on the Tinseltown Starliner, I never dreamed his first voyage would be his last." However, the conductor later calls the train for the day the final run. By definition, it would be Abe Simpson's final ride on the Tinseltown Starliner, only because the train would no longer run.