Other mistake: Poor guy George obviously has his heart on the wrong side - that is at least where his hand goes when he suffers his heart attack.
Factual error: Charlotte is seen speaking on a Princess style phone in the movie. The phone she is using has a modular plug in the handset. Modular cords were not used on Princess phones until 1975. The movie takes place in 1962.
Continuity mistake: In the final scene, after George falls to the floor with a heart attack, the alarm clock is knocked onto the floor but the position changes from near his elbow (in the overhead shots) to closer to his hand (in the floor-level shots).