Fast forward the movie until Sandy and Danny get in the car at the very end when the car is about to take off. They both have there jackets on! When Danny first saw Sandy's "make-over" he threw his jacket off and in to the crowd as did Sandy. I don't think they had time to go to the mall and get a new one.
could they not have picked them up again? it's not like they had the car with them, either, so they must have gone back to get THAT at some point!! they could have picked up their jackets then!
actually watch the movie again. You will see that Danny threw off a letterman sweater. Many Danny's T-Bird Jacket was in a car or something ever think of that, and maybe one of Sandy's friends picked up her coat for her.
Danny had his letter sweater on then took it off. Sandy had her jacket hooked on her finger slung behind her back.The Pink Ladies gave Sandy her jacket back to her,So I think the T-Birds gave Danny his?