Selina's beads are mixed up from the night before she goes to the park. Then supposedly Gordon upsets the box of beads again.
After Selina puts crackers in the paper bag, she rolls the top of it, but when she turns around, she is seen rolling it down again.
In the beginning, Rose-Ann comes home and sits on her bed. She is seen taking her shoes off twice.
When Gordon is teaching Selina to use the payphone, the scene begins with his tie just being casually flipped over. When the camera returns to him midway through the scene, it is tightly knotted.
When Mark walks into the door of Gordon's apartment, he is shown closing the door behind him. When the shot cuts back to him, he's beginning the process of closing the door behind him again.
When Gordon and Selina first meet in the park, the interactions between them would hardly have been perceived by the public as innocently as portrayed in the film. In 1965, a black man putting his hand down the back of a whimpering white girl's blouse, and then knocking over her beads while she screams, would have brought a severe reaction down on Gordon from white people nearby. In fact, in the novel, Gordon gets jumped and beaten up in the park during his attempt to free Selina from Rose-Ann at the end of the story.
When Selina reveals her sexual assault (at the age of 18-19) to Gordon, the viewer sees her attacker and her struggle through her eyes; this is impossible, because earlier she explains the cause of her blindness at the age of five. However, it is not supposed to be Selina's actual POV; the camera shot is used to put the viewer in her shoes and experience what happened to her.
When Sidney Poitier as Gordon squats down to give Selina the pineapple juice, he temporarily loses his balance. However, he just keeps on talking and the camera keeps rolling whilst he regains his balance.
However, this should not be considered a Goof, as people do sometimes lose their balance when they jump, squat, or even simply walk.
When Selina goes out to the street alone for the first time, a woman (an extra) standing very still can be seen waiting for her cue to walk, reflected on the restaurant glass window.
When Gordon is walking Selina to the deli, people on the bus are waving and looking at the camera.
Obviously anticipating a scripted slap even before there is any reason to believe she'll be struck, Selina visibly flinches before Rose-Ann suddenly smacks her across the face.
When Selina is alone in the park at night the evening Gordon had given her pineapple juice and is inspecting her necklaces in the box right before she disappears behind tree, there is a brief unexplained flash of light from what is probably a camera bulb from a studio photographer taking a publicity shot.
When Rose-Ann and Sadie are standing in front of a booth selling magazines, the New Yorker magazine hanging behind them is the December 19, 1964 issue even though the movie takes place in the summer.
Before Rose-Ann walks out the door, Ole Pa yells, "Drop dead!", but his lips don't move.
Gordon's music box continues playing after Selina closes it.
When Selina whistles "Somewhere over the Rainbow", she stops whistling to breathe in more air, but her whistle can still be heard even though her lips aren't together.
Throughout the movie, crew members and the boom mic can be seen reflected in Selina's glasses.
(at around 1h 8 mins) The camera's reflection can be seen in the window.
When Gordon begins teaching Selina how to navigate the park he tells her that the sun is "roughly in the south this time of day". The sun does not move north or south during the day, only over the course of months between summer and winter. He would've been correct in saying "this time of year".