Goofs

When Charly is talking to Mrs. Kinnian outside the building for his night class, he's wearing a gold vest. When the camera cuts back to him after Mrs. Kinnian enters her car, he's wearing a blue vest.

When Charly comes back to his room, disgusted that he had been beaten by a mouse once again, he throws his hat onto the dresser and it falls to the floor. He leaves moments later and the hat is back on top of the dresser.

When Charly and the other employees leave the bakery for a beer, Gimpy (Ed McNally) has lost his limp and is walking normally.

In the lounge scene where Charly assists the mentally challenged busboy, his hair switches back and forth from dry to slicked back.

In the split-screen shot in which Alice Kinnian showing Charly a picture of a family and asks him to make up a story about them (shot from opposing angles and supposedly simultaneous), on the left side she is holding up the card at its top with her left hand, with her right hand reaching in front of it, while on the right she is holding up the card at its bottom with her left hand, and pointing over its top with her right hand.

There's a scene where Charly has just awakened after surgery. The next scene shows him working on a puzzle and he has a full head of hair and no bandages. If he'd just undergone brain surgery, he should still be wearing bandages or at least have a shaved head.