Revealing mistake: Outside the church, Allnut tosses a cigar down knowing it will attract the natives. Notice how one extra, one of the first to arrive, grabs the cigar right away, but still pretends like everyone else to be looking for it left and right with great clamor, so that the scene can continue. (00:04:35)
Character mistake: Breaking the news of war to the Sayers, Allnut tells them that the war is involving smaller nations like "Austria, Hungary, Belgium, Spain." Spain was not amongst the participants of WW1. (00:10:00)
Continuity mistake: The reverend and his sister get on their knees to pray for England as Allnut leaves with the news of war. Reverend Sayer has his jacket unbuttoned; hearing the shout from the villager announcing the Germans' arrival, his blazer is suddenly buttoned up when he rushes to talk to him. (00:11:00)
Continuity mistake: The reverend shoves aside a German officer and gets smacked in the face with a rifle. Robert Morley sports heavy blue makeup, a not-so-believable instant ecchymosis. In the next scene the village ruins are still smoking, but his face is clean; the bad bruise and little cut on the lip have vanished without a trace. (00:12:00)
Revealing mistake: The Germans burn the whole village and deport the natives...who don't seem all that concerned. You can spot some being rather casual about it, and smile as they get herded away - like the woman in the blue dress. (00:12:40)
Visible crew/equipment: When Rose is calling his brother who is working the burnt out ground of the village, in the long shot the man stands up straight as she approaches, while in the close-up, Robert Morley is still more hunched over. And really, the person in the long shot does not even look like Robert Morley, but a body double. (00:13:15)
Continuity mistake: After the death of her brother, Katharine Hepburn is sitting on the porch. The knitting kit on the table is showing some blue fabric peeking off the lid, and there's a reel next to it. In the close-up that follows, white fabric is showing (the blue one is on the opposite side, barely visible) and the distance of the reel has changed. (00:16:20)
Continuity mistake: During the conversation on the porch that follows Samuel Sayer's death, Katharine Hepburn is obviously lit differently depending on the camera angle; in close-ups her chest is fully shadowed, while in the wider angles (with Bogey in frame or not), light reaches the first button of her dress. (00:17:25)
Factual error: This comes directly from the novel, but the Ulanga river the protagonists are traveling by boat to reach the lake with the German battleship, does not in fact encounter or form any lake in its path. It also travels towards northeast, so the opposite way of what the map shown in the movie indicates. (00:22:00)
Continuity mistake: When Bogart responds "The Louisa, miss?!" to Rose's idea of torpedoing it, he is suddenly with his right fist in the air instead of clutching the other wrist. (00:25:05)
Continuity mistake: Allnut is having his gin waving the bottle under Rose's nose; as he asks "You're gonna have one, Miss?" there's a close-up of Katharine Hepburn' holding the handkerchief to her face, unlike the previous and following shot. (00:29:30)
Continuity mistake: Everything is suspiciously dry under the little makeshift tent Rose closed with her clothes, including the floor she sleeps on. When she opens the umbrella to repair Mr. Allnutt, it's wet already. (00:37:05)
Revealing mistake: During the crossing of the rapids, in several shots you can see a white (possibly green if you are looking at a video version that came out before the 2009 restoration) halo around the actors, in particular the hat and hair. (00:38:15 - 00:39:05)
Revealing mistake: During the crossing of the first rapids, in the faraway shots Bogie and Mrs. Hepburn were replaced by mannequins - you can see how still they are throughout the bumpy ride, the lady in the hat sitting perfectly upright. (00:38:20)
Continuity mistake: After crossing the first rapids, Humphrey Bogart's shirt appears to be mostly wet in the back. When he talks to Miss Sayer, it's the front of it soaking wet. (00:39:15)
Revealing mistake: When Charlie pours himself a drink by adding gin to a glass he filled up with river water, a little conjuring trick is at hand here; the glass Bogart spikes is not the same one he legitimately dipped into the murky river. He puts the dirty water glass out of frame and supposedly retrieves it once he opened the bottle, but it's from a different spot. More telltale signs are the difference in level of liquid, and in fact, at the beginning of the sequence once he pulls the glass back from the river, above the edge of the boat railing you could see the rim of the other glass ready to be switched. (00:40:40)
Continuity mistake: Rose calls a drunk Charlie "a coward." He turns around, and you can see the difference in the way he wears his ascot, way wide on his right side of the neck, as opposed to before. (00:42:10)
Continuity mistake: When the Germans at the fort fire the first shot, Bogart is ducking while Katharine Hepburn is sticking her head out, hand on the edge of the boat. Immediately after that, she is shown ducked down and with her hand closer instead. (00:51:05)
Revealing mistake: Before the boat gets into the steep rapids following the bit with Allnutt doing hippo and monkey impressions, the wide shot shows the mannequin supposed to stand-in for Bogart all bent over in a way that does not mirror the actor at that point (but fits the bit when the boat is taking a nosedive). (01:02:40)
Continuity mistake: Rose offers Charlie to help with the propeller. He says "Here goes" and motions to go back underwater. Katharine Hepburn's hands are on the vertical supports sticking out. Not a moment has passed (you hear the plop of him actually submerging) and in this new reverse shot her hands are by those same supports, not on them. (01:07:15)
