re: robe goof.
Re:"Bathroom scene at flight attendant apartment, Doris Day is wearing her personal robe. Monogram with DDM can be seen on the back."
This may not be a goof.
The monogram on the robe is DMD, two smallish Ds with a big M in the middle. The owner of the apartment and presumably the robe is the other air hostess,Denise Martin (played by Aline Towne). We are told her name several times during the course of the film.