Revealing mistakes: When the boat crashes into the rock a panel can be seen sliding over to reveal the hole in the boat.
Revealing mistakes: When Ethel and Norman are watching the loons from their boat, there are obvious decoys placed where the loons should be. The decoys aren't even in the correct shape of a loon.
Crew or equipment visible: When Billy Ray is circling the sailboat in the lake, you can see the shadow of helicopter used to film the scene.
Continuity: When Norman lets Billy Ray go off in the boat by himself, we see him speeding across the lake. Billy Ray and the steering wheel are on the alternate sides of the boat in subsequent shots.
Continuity: When Ethel and Norman first drive to Golden pond it's supposed to be early spring, but there is a close up of Queen Anne's lace, which is a flower that blooms in late summer.
Boom mic visible: As Ethel and Norman prepare to leave the dock after gassing up the boat, the microphone boom is reflected in the boat's windshield. It moves each time one or the other actor speaks.
Continuity: When then mailman comes earlier in the movie, the screen door is broke; but a few scenes later you can see when the door is open it goes back to the closed position. Later on it is broken again.
Continuity: There are windows on the landing of the stairway up to the second floor. When Chelsea and her new boyfriend the dentist and the dentist's son arrive it's dark outside. But sunshine is coming through the windows on the landing. Whereas all other windows are showing dark. And the time is verified that it is dark outside when Chelsea comes into the house and greets her father.