Continuity mistake: When Sheela, Pru and their two dates leaves the house, Giddy is seen sitting upright by the table. When it cuts to a close-up of Giddy, she leans onto the table while resting her head on her hand. (00:38:05)
Continuity mistake: After her wedding to Jack Lemmon, Ann-Margret says goodbye to Walter Matthau by kissing him on the cheek. When the camera shows her, she places her left hand on his face. When the camera shows him, her left hand is on his shoulder. When the camera returns to her, her left hand is back on his face again.
Continuity mistake: During Waverly's first chess match, her opponent makes a move, resulting in a board where the white knight and white king occupy non-adjacent squares. In the subsequent close-up shot, the white knight and white king suddenly occupy adjacent squares. Still in the close-up, Waverly picks up the white knight, but then is no longer holding it until partway through the next shot. Finally, Waverly picks the piece back up, places it down, and calls a (rather dubious) checkmate.
Continuity mistake: Towards the end of the movie when Don cannot sleep and goes to the cafe where he sees Jim, he enters the cafe and it is dark and raining. A few minutes later during the shots where the camera is on Jim, the window is behind him and you can now see it is very light outside.
Continuity mistake: When Josh and his father play a game of chess Josh's father picks up a piece from the centre of the board and moves it diagonally towards one of the flanks. In the next shot it is visible that the piece is a white rook, which can't move that way. Plus the previous shot shows both white rooks still standing in their original positions on the board. (00:15:55)
Continuity mistake: In the scene where Ellen and Newland are seated in her living room by the fire, we see her take a cigarette holder charm off of her bracelet. Then, the next scene shows a closeup of the cigarette holder charm, and she is again removing it.