During bookstore scene, a counter top display of a book by author/performer Steve Allen (whose wife Jayne Meadows appears in a major supporting role) keeps flip-flopping so cover is always on view, whether it is being shot from point-of-view of a customer or from that of behind counter clerk.
The shaving cream on Ben's face while he's on the phone to Mexico progressively disappears during the course of the call.
John is wearing the stripes of a Buck Sgt - but his service cap has a gold band indicating he is a commissioned officer. His awards indicate he was in a combat zone, but is not wearing his combat unit patch. He is also wearing his name tag on the wrong pocket.