When Birdie is working in the photo lab, she accidentally ruins a customer's pictures. She said she loaded the paper wrong. That wouldn't ruin the negatives. Negatives are processed film to expose an image, no paper is involved.
When Bernice walks into the classroom, the teacher is going over grammar sentences and correcting them. When Bernice walks back to the back of the classroom, the girl sitting next to her is holding a science book.
When Gena Rowlands' character drops the cup and saucer, the cup falls upside down, spilling all the tea. The cup then slides, upside down and completely empty, away from the edge of the bedside table, while the saucer falls to the floor. The next shot of the cup and saucer show the saucer on the floor and the cup, still containing tea, falling onto the saucer.
At the funeral (which appears to be a Catholic service), there's a closing liturgical dialogue in which the priest says "God be with you" and the people respond "And also with you." This is incorrect--the priest should have said "The Lord be with you."
When Birdee is sitting with Bernice on her bed after her father has just left her, Bernice tries to rub her eyes by first going under her glasses then she goes right through her glasses where the lens should have been.