The home movie Stella and Alice made clearly shows the two setting up the camera outside the bedroom window. When the video is played in school, it starts her answering the door and then later in the bedroom.
Will and Herby are in the helicopter flying around trying to find Skeeter Doogan. In the shots of them in the helicopter, it appears to be clear outside but when they are looking at the ground, you don't see any shadows from the trees or bushes. This would indicate that it is cloudy when they filmed the shots from the helicopter to the ground.
P.T.A. stands for Parent-Teachers Association, therefore there would not be a miscellaneous group of people in the town running it. The P.T.A. would be made of of parents whose children attend the school.
The home movie Stella and Alice made on the sly is in Super 8mm, but the educational film they supposedly snipped it into is in 16mm.
The helicopter's shadow can be seen during an aerial scene.
The date, September 8th, 1968, was a Sunday, not a week-day, (for school, teachers and students). Dee Johnson mentioned the date, as she was postponing the election voting, from an immediate start, that Mrs. Flora Simpson Riley had planned on.
Will and Stella are leaving in Will's helicopter to get married at the end of the movie. Neither of them are wearing safety belts and neither is wearing a headset. Will would have to be wearing headphones to stay in touch with a control tower or other pilots in the area. Stella would need to wear a headset to talk to Will over the noise of the helicopter's engine.
The scene at the race track was obviously not filmed in Ohio. There are palm trees in the distance.