honestly, he'll panic before he leaves the flat when he can't find it anywhere, but he's also got a bunch of other people's stuff to unload too and he'll at least try to do that first. but once he notices all the treasure littering the beach, it'll be a natural progression to assume he just dropped it somewhere in the sand somehow.

joke's on leslie though since someone else ended up with it so his and zack's search will be for naught.