What if a team unintentionally skips a task?
Well, it seems to depend. In TAR3, Derek and Drew got lost looking for the Roadblock clue and managed to accidentally find the pit stop mat. They were told to go back and complete the Roadblock. But in TAR1, Davey and Margaretta accidentally skipped a Roadblock. The Roadblock would have had one of them walk partway up the Eiffel Tower and spy a TAR flag on the Arc de Triomphe with a telescope. According to the episode recap on TWoP, “It seems that when they got to the Eiffel Tower, they ran right past the flag at the bottom that explained what they had to do. Through a combination of luck, guessing, and presumably seeing other teams running around, they (both) ran up the tower, where they got the skinny from Paul about the clue, and figured out that they should go to the Arc. Technically, this is a rules violation, because they both ran up the tower, which means that neither of them completed the one-person-all-alone-goes-up-the-tower task.
