Continuity mistake: After fishing on the Niagara river with the Cutler's, Mr. Kettering pulls his boat up to a dock that is in the shade. In the next shot the dock is in the sunlight. (01:11:30)
Continuity mistake: Marilyn's lover writes a one line message to her on a postcard and places it back into the postcard rack. She walks over and reads it and we now see that there are 6 lines written on the back of the card. (00:34:05)
Continuity mistake: After George Loomis shuts the lights Polly Cutler looks to the left at the falls in the dark, through the back window. This is the wrong direction as we see later in the movie as Marilyn has to look to the right to see the falls during the day. (00:23:15 - 00:36:15)
Continuity mistake: As the Cutlers drive into the Rainbow Cabins it's clear to see that Polly's vent window is closed. She doesn't touch it but when the manager helps her out of the car it's open. (00:07:10)
Continuity mistake: The Cutlers drive up to the Rainbow Cabins and Ray reaches for the ignition to turn the car off as they speak to the manager. In the next shot his right hand is leaning on the front car seat. (00:06:30)
Continuity mistake: The manager knocks on the door to cabin B and the stone post in the background on the left of the screen is in direct sunlight. Two minutes of uninterrupted movie time goes by but as the Cutlers get ready to leave the stone post, and the falls behind them are no longer in direct sunlight. (00:08:00)
Continuity mistake: Ray Cutler says to the customs officer, "I'm going to catch up on my reading" and his right arm is leaning on the seat of the car. In the next shot his arm is at his side. (00:05:45)
Continuity mistake: Marilyn walks up to the ticket booth and gets a refund for one of the tickets to Chicago that she bought earlier in the movie. Looking at her luggage we see no marks on it at all. She picks it up the same way she puts it down, but in the next shot a large black mark appears on the front of it. (01:01:15)
Continuity mistake: As Polly Cutler lays out on a beach chair sunning herself Ray steps back and decides to take a picture of her sitting there. Niagara Falls, which are always seen behind them are not in this shot, which has obviously been filmed on a sound stage. The bushes against the stone pillar are also different. (00:34:55)
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: 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)
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: 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: 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)
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: When the Cutlers drove into the Rainbow Cabins, the manager threw the newspaper he was reading onto his rocking chair. No one goes near it but when we see the chair again, as he speaks to Marilyn, the newspaper is not there. (00:09:05)
Continuity mistake: After the Cutlers leave the customs officer, Polly says to Ray, "Delayed or not" and the bottom half of her face has a shadow falling across it. In the next shot it's gone. (00:06:05)
Continuity mistake: Sunlight is coming into this room from all directions. At first it is coming from the right of the screen. Then when Denis O'Dea goes into the kitchen (screen left), sunlight is coming from the other direction. (00:48:40)
Continuity mistake: Marilyn sleeps in her hospital bed as the song "Kiss" plays from the bell tower. At first she's sleeping on her back then in the next shot she's on her side. (00:57:15)
Continuity mistake: George Loomis chases Polly at the Cave Of The Winds and she almost gets killed braking apart the wooden rail as she runs into it. The part of the railing hanging on the left changes position between shots. (00:54:40)
