Back in the 1990s, I kept hearing rumors & I think official announcements that a remake of “It’s A Mad (x4) World” was being planned. Of course, nothing emerged, but then “Rat Race” is released. Was this the planned remake that turned into a different movie?
I think Rat Race was closer to a remake of the Cannonball Run, or Gumball Rally. Which may each have been remakes of It’s a Mad Mad Mad Mad World.
A sequel to It’s A Mad Mad Mad Mad World, to be entitled It’s A Mad Mad Mad Mad MAD World, was announced last year, I believe. As for Rat Race, there are a number of similarities to Mad World, but to other films as well- heck, in the '80s, there was a similar film called Million Dollar Mystery which was part of some sort of Glad Bags sweepstakes.
It wasn’t intended to be a remake (as far as I know), but rather, just another film in the same plot family (multi-participant treasure hunt-race). And, IMHO, it was funnier.
*Rat Race * also seems similar to Scavenger Hunt.
It depends on if “same plot” = “remake”