Continuity mistake: When Rosemary has decided to sneak over to the Castevet's, she removes the towels from the closet shelves. She then tries to shut the door by pushing the towels (on the floor) into the closet. We see that the closet door does NOT shut all the way. Rosemary goes to get a knife, when she gets back to the closet, the door is completely shut, and she must now turn the knob to open it.
Continuity mistake: Rosemary tries a third time to figure out the anagram with the Scrabble letters and comes up with "elf shot lame witch". She tries a fourth time and comes up with "how his hell fact me". She decides to give up and begins putting the letters away when she has an idea and pulls the book close to her and we see the wrong set of letters back on the floor "elf shot lame witch".
Factual error: Rosemary calls Dr. Hill from a pay phone and says, "The baby's due on Tuesday, you remember you told me June 28th" (and June 28th 1966 does fall on a Tuesday). In the previous scene in Dr. Sapirstein's office his receptionist is making an appointment "next week" for a patient and that date is "July 10th" indicating that if Rosemary is due on June 28th (which she says is next Tuesday) the dates do not match and it must still be the week of June 20th which is at least two weeks before July 10th.
Continuity mistake: Before she enters their apartment and sees her baby, Rosemary walks back to the closet that connects her apartment with the Castevet's and as she opens the door we see yellow linens on the top shelf. Several shots before as she takes the shelves down these yellow linens fell on her head and were not put back on the shelf.
Continuity mistake: Rosemary gets back into the apartment and gets Elise Dunstan's phone number from the phone book inside her pocketbook. She leaves the pocketbook right next to the phone book but when Dr. Sapirstein comes in the with a sedative she tries get away across the bed and the pocketbook is no longer there.
Continuity mistake: After Rosemary speaks to Dr. Sapirstein's receptionist about an appointment she sits down in the waiting room and the receptionist asks her how hot it is outside. She doesn't move yet several things move behind the receptionist's head in the two shots she's in. The ash trays above the windowed file cabinet behind her move from the right side to the left side and the two small file cabinets above the large file cabinet to her right also move.
Continuity mistake: After telling Guy that she doesn't want Minnie or Roman setting foot in their apartment again Rosemary sits down in their living room and reads from the book "All Of Them Witches". If you look closely at the second shelf in the bookcase on the left of the screen several books (primarily a red one) have been added between shots.