Other mistake: The first time Corie arrives at the apartment we see her climb each flight. For the last one, the one that's supposed to take her to the top floor, we can see the underside of another flight above her head. By the time she hits the top of that flight and her walk to her apartment door we can see there are no more stairs. The fact that they live on the top floor is discussed throughout the film, especially when addressing how exactly Victor Velasco can be their "upstairs" neighbor. (00:10:20)
Continuity mistake: In the park scene where Paul's drunk and barefoot, Corie carries his shoes as she follows him back to their apartment. When they're in the apartment Paul has his shoes on, and Corie helps him take his wet shoes off.
Other mistake: When Corie's mother arrives for dinner, she sits down on the trash can, and asks Paul to get her pink pills from her handbag. When Paul holds out the open pill box to her, the mom accidentally knocks it shut, but pretends to grab a pill anyway, and take it.
Continuity mistake: At the end, when Paul and Corie are out on the ledge of their apartment block, Ethel and Victor join the crowd on the opposite side of the street, who are all looking up, to see the couple kissing and heading back in. But when there's a crowd shot, when the crowd is seen from the ledge viewpoint, Ethel and Victor are missing.
Other mistake: After a night of drinking ouzo, Corie asks Victor if she'll have much of a hangover, not having drunk ouzo before. Victor says no the hangover, but she won't be able to make a fist for 3 days, and when she tries, she can't make a fist, but seconds before Victor spoke, Corie did make a fist, a big one.
Continuity mistake: When Corie decides to meet Paul at the bus stop, she clings to his right side, but from the front view she's now clinging to his left side.
Character mistake: Corie goes into the empty bedroom and says "The bed is six feet long" as she measures it out with her feet "and the room is five and a half feet, and I'm in big trouble." But she only measured the width of the room, not the length.
Continuity mistake: When the telephone man comes to install the phone, his workbox is under his left arm then suddenly it's under his right arm.