They didn't make this film soon enough; I mean, even five years earlier and Harrison Ford wouldn't have been quite so battered from the stuntwork.
Did anyone notice (not sure where--the camp, the truck?) that Indy flipped a line from RLA? In "Raiders", he says, "It's not the years, it's the mileage." In response to Marion in KCS, he replies, "It's not the mileage, it's the years."
The presence of HF as Indy is a given (it's called "Indiana Jones and the Kingdom of the Crystal Skull"-- duh! D'oh!); when I heard that Marion was showing up, I really wanted to see this movie (I wanted to find out what she was going to do to him *this* time...).