After Bobby and Carl are finished playing Ping-Pong, Carl leaves in the blue station wagon to go to the mainland where he spends the night. In the next several scenes when Bobby and Catherine spend time together while it is understood Carl is away, they are seen cavorting outside where the blue station wagon is shown parked in the driveway.
A full rack of ten pins appears after Rayette picks up the spare following her gutter ball. This is correct but since it is the last frame of the second game, she gets another ball, which is not taken.
When Bob and his sister return from drinking coffee on the water front he no longer is holding his brown coffee mug. When the camera angle changes to show them walking up the porch steps the cup is not present.
While Tita and Bobby are on the waterfront, talking, Tita is leaning on the tree with no coffee cup and in the next shot she is holding a coffee cup. In the next shot, the cup is gone and she is leaning on the tree again.
During the ping-pong game between Bob and Carl, in the background you can see Spicer cleaning the wheelchair on the right side. When Carl is returning from retrieving the ping-pong ball that went under the car, you briefly see Spicer on the left side of the wheelchair.
At around 55 minutes into the film, when Robert opens a door to find Partita giving their father a haircut, the head of a crew member hidden behind the open door is reflected in the mirror above the fireplace. The crew member moves slightly just before the scene cuts to Robert standing in the doorway.
Bobby tells Raye that he has to go to Washington State to see his father who had a stroke. The Dupea household was actually on Central Vancouver Island in British Columbia, and the ferry scenes occurred at Brentwood Bay and Mill Bay, which are also on Vancouver Island, not Washington.
Rae is taking a Polaroid picture of Bobby as they drive up to Washington. In the very next scene it is already developed. Polaroids do not develop instantly; Polaroids of the day took at least five minutes to be fully developed.
When Bobby plays the piano for Catherine about three quarters through the movie, the music in front of him is clearly not what he is playing (Chopin's "Prelude in E Minor"). On one hand, this emphasizes his improvisational nature and rejection of the life prescribed to him by his class, but it also shows his musical prowess and memory. He reveals that the song was memorized when he later says "I picked the easiest piece I could think of".
During Bobby's monologue with his father at about 1:27:30 there is an onlooker in the far background in the top left corner of the frame. After 15 seconds they walk away, giving themselves away as a person rather than a tree stump.