Why didn't the nurse think it was peculiar that Marty had on a hospital gown under her coat? That was pure directors blunder.

Because on a soap,all background personel are always written as idiots.Someone should have had their eyes on Marty at all times.

All medical personnel on soaps are required to be ignorant to the obvious, it's how they get silly plots to move. It's funny, though, I recall reading from a long time OLTL viewer once that when baby Kevin was kidnapped out of the nursery at Llanview Hospital, Dr. Jim Craig made it a point to state how the security breach would be thoroughly investigated. Back then far-fetched calamities happened, but they tried to interject enough logic and rational into the situation as possible, and as a result, viewers intelligence weren't insulted as much.