Revealing mistake: When the boat is supposedly surrounded by a swarm of flies, they're really just relatively few flies trapped between two panes of glass in front of the camera lens. Evidence: whenever the camera moves, the "swarm" moves with it against the background, and you can even see some of the insects walking on the surface of the glass.
Continuity mistake: When Charlie Allnut grabs a bottle of gin from the box, all the bottles in it are wrapped with paper for transport. But when Rose Sayer takes the bottles out of the box to empty them into the river, the paper is gone (from the movements of her hand/wrist, you can tell that she doesn't unwrap the paper from the bottles).
Continuity mistake: In the scene where there is a terrific storm while Bogart and Hepburn are asleep, Bogart gets extremely wet before being invited into the shelter by Hepburn. Upon entering the shelter and lying down to sleep, Bogart's blanket is perfectly dry.
Factual error: During the last scene, after the German gunboat sinks and the two main characters are thrown into the lake, both Bogart and Hepburn are swimming toward the shore of the lake. Even though there is nothing which could reflect the sound of the two swimming and splashing water, one can hear the echo of water splashing. Apparently, the last scene was filmed in a pool on a sound stage.
Factual error: In the scene where the German East African troops are shooting at Bogart and Hepburn, their rifles are Gewehr 88 "Commission Rifles'" with five-shot magazines. In actuality, the German East African troops, under the command of Colonel Paul Von Letow-Vorbeck, were equipped with the absolute dregs of the Kaiser's arsenal: Gewehr 71 single-shot rifles, and Gewehr 71/84 8-round tube magazine rifles whose magazines usually got fouled and had to be used as single-shot rifles anyway.
Factual error: The scene where the German officer is blinded by the sun and thus can't shoot at Humphrey Bogart could never have happened. The Imperial German East African Army had no rifles capable of accepting a telescopic sight. In fact, throughout the war, its commander, Colonel Paul Von Letow-Vorbeck, had his marksmen trained to use open sights, not scopes. The rifle used in the scene was a British Lee-Enfield No. 1 Mk. 1 modified to accept a telescopic sight, which would have been scarce in Africa, even in the British Army. But it couldn't have been captured, as unit armorers in the British Army began scoping Lee-Enfields in mid 1915.
Continuity mistake: In the scene where Humphrey Bogart and Katharine Hepburn are taking a bath in the river, Katharine starts off looking as if she is bathing fully undressed. As she climbs into the boat, however, she is clearly seen with a full set of underclothing that includes shoulder straps which were not there earlier.
Continuity mistake: When Rose and Charlie are getting married on the Louisa, one camera view of the couple shows a small island in the background, about 50 yards off the port side. The island stays in the exact same place in all subsequent shots from that angle, indicating that the ship is stationary. When they cut to shots looking towards the bow of the Louisa bearing down on the capsized African Queen, it is traveling at a good pace, as evidenced by the bow wake.BocaDavie
Continuity mistake: When the African Queen finally passes the fort, in the final few seconds you can see somebody standing in the back of the boat. Both Charlie and Rosie are still crouched down low in the next shot.
Revealing mistake: In some parts of the movie, the boat used is diesel powered. In one particular scene the viewer can plainly see the diesel exhaust from down low on the stern as well as small wakes on the surface of the water from the exhaust passing above it.
Revealing mistake: Charlie calls Rose to take the tiller, for the first time. She has a hamper on her lap, but there's nowhere to put it, so she takes it out and lowers it down below the bottom of the screen, then she takes her hands away and the hamper quickly disappears. Some crew member must have taken it away.kh1616