Continuity mistake: Marilyn's shadow falls on the door as she speaks to Mr. Qua and the Cutlers, and after finishing she goes back into her room. In the next shot the lighting has changed and Mr. Qua's shadow falls in the opposite direction onto the Cutlers as he speaks to them. (00:09:30)
Continuity mistake: Mr. Qua and the Cutlers walk away from the Loomis' room after talking to Marilyn. If you look closely the stonewall to the left of them is not in direct sunlight as it was a few shots earlier when they walked up to the door. (00:09:45)
Continuity mistake: Ray Cutler drives off to park the car as Polly stands alone in front of the Rainbow Cabin's office. On the left of the screen we see a curled up garden hose leaning against a small pine tree. No one went near it, but earlier it was in front of the pine tree. (00:10:00)
Continuity mistake: Mr. Qua and the rocking chair that he's sitting in as the Cutlers pull up, are in the shade. Now a few minutes later, Marilyn walks past Polly as she leaves the cabins, and the rocking chair is in direct sunlight. (00:10:05)
Continuity mistake: Marilyn walks past the office as she leaves the cabins, and the blinds on the window are down. No one was in the office, but several shots earlier, as the Cutlers drove in, the blinds were up. (00:10:10)
Continuity mistake: As the Cutlers set sail on the "Maid of The Mist" it's mid-day. Two shots later we see the boat in a long shot and it's late afternoon. (00:11:45)
Deliberate mistake: Jean Peters' face is dry on the Maid of the Mist boat ride. (00:12:00)
Other mistake: In Canada the Cutlers take the Scenic Tunnel tour, and if you look closely the cash register keeps ringing up zero as they and the people in front of them purchase tickets. (00:12:20)
Continuity mistake: The Cutlers take the Scenic Tunnel Tour and the attendant on the left is handing a gentleman a pair of boots. In the next shot he's standing around getting ready to laugh. (00:12:40)
Continuity mistake: At the bottom of the Scenic Tunnel Tour, Polly runs into Marilyn kissing her lover. At first the gentleman has his hands around her waist. Then in the next shot his right hand is holding her face. (00:13:45)
Continuity mistake: Both Marilyn and Jean's faces are dry as bones in the scene below Niagara Falls but Marilyn's lover is drenched. (00:13:50)
Continuity mistake: At night the Rainbow Cabins has a little outdoor party. The Cutlers are dancing together, and when the song stops Ray has his arms around Polly's shoulders. In the next shot his arms are around her waist. (00:16:35)
Revealing mistake: As Marilyn walks out during the outdoor party at the Rainbow Cabins, we see an artificial painted backdrop of Niagara Falls behind her that is nowhere near the actual falls that we saw earlier in the movie. (00:17:20)
Continuity mistake: During the outdoor party at the Rainbow Cabins Marilyn walks out and asks the DJ to play "Kiss". No one goes near them but the three chairs that she passes on her right move about a foot closer to the record player when she walks away. (00:17:30)
Revealing mistake: During the outdoor party at the Rainbow Cabins Marilyn asks the DJ to play "Kiss" in order to drive her husband George nuts, and after a couple of minutes he comes out and smashes the record. As he walks back to cabin B it's obvious this is a set as there's nothing inside the room except a blank wall. (00:20:15)
Continuity mistake: Polly Cutler enters cabin B in order to put some Mercurochrome on George Loomis' cut hand. At first the yellow notice on the left door post is entirely in the light, then in the next shot as she walks through the door the lighting has changed and it's in the shade. (00:20:45)
Continuity mistake: George Loomis throws a lit cigarette at the ash tray on the table to the right of the door as Polly Cutler knocks. We see the cigarette smoldering on the table but two shots later after she enters we see the same spot again and it's gone without anyone going near it. (00:20:50)
Continuity mistake: Polly Cutler enters cabin B in order to put some Mercurochrome on George Loomis' cut and the do not disturb sign on the door knob is tilted to the left. No one goes near it but later in the scene it's been set straight. (00:22:55)
Continuity mistake: After Polly Cutler enters cabin B in order to put some Mercurochrome on George Loomis' cut hand the model car that he has been assembling sits on the table to the right of the front door. It moves closer to the ashtray as the scene progresses. (00:22:55)
Continuity mistake: As George Loomis goes over to the front door and shuts the lights so that Polly Cutler can see the falls in the dark, a pink sweater appears on the red and white chair behind him. (00:23:00)
