When Ned walks up to the boy selling lemonade his hands are by his sides but in the next shot they are on his hips.
At the Biswangers, when he is pushed, Ned's positioning in the close-up does not match the other shots.
When Shirley is wearing a pink bathrobe on the other side of the pool, she picks up a red folder and knocks some pens and pencils off the table and picks up one of two pencils still on the table. When she gets up and leaves, there are more pencils on the table than in the previous shot.
When Shirley covers Ned with a towel, in one shot it is draped over both of his shoulders whereas in the other shots it's only over his right shoulder.
When Julie leaves with Ned on his journey, she is bare footed. Later, at the Bunker's pool, she discards a pair of shoes.
When Ned and Julie are walking through the field, they both comment on the flowers visible, calling them marigolds and stating they usually aren't in bloom at that time of year. The flowers are Black-eyed Susans (Rudbeckia), not marigolds. If they were marigolds, in Connecticut they would be in bloom during the summer and early fall just as the Black-eyed Susans.
Ned arrives at the Westerhazy pool, swims three laps, jumps out and talks to Mr. Westerhazy. All this in front of Mrs. Westerhazy, and she acts surprised to see him.
Mrs. Westerhazy may have been asleep and didn't see Ned swimming.
Mrs. Westerhazy may have been asleep and didn't see Ned swimming.
In the second shot of Ned pounding on the door of the empty house, the film is being run backwards - it's the same shot as before the interior of the house is seen through the broken window.
Shadow of the camera and light-rig clearly visible at the first pool party on the backs of Ned and Julie as it swings around behind them.
When Ned is crossing the highway, bystanders can be seen on an on ramp.
When Ned is home, the tennis courts have tire tracks across them.
At the pool with Ned (Burt Lancaster) and Shirley (Janice Rule), a camera shot shows a palm tree in the backyard. Palm trees can't survive in the climate of Connecticut, where the film allegedly was filmed in its entirety. Perhaps when the scene was reshot with Rule replacing Barbara Loden, location shooting had already wrapped.
While at the Grahams' pool, both Betty and Howard claim their pool filter filters out "99.99.99% of all solid matter".
Such a number with 2 decimal points is not possible.
They probably meant "99.9999%".
Also they pronounce the numbers after the decimal point as "ninety-nine" which is incorrect, all numbers after a decimal point are pronounced individually i.e. nine, nine, nine, nine.