When the widowed ape is holding George (Crosby) in her lap, Crosby's socks switch between red in one shot and pale yellow in the next shot. Skipping back and forth - the scene must have been filmed over more than one day.
When George, Harold and Lala are chased away from the African Queen by the tiger, Lala has flowers at the back of her hair. When they entered the village in the next shot, the flower display is over Lala's right ear.
When they are on the island, Lala has no flower in her hair, then flowers at the back of her ponytail and then a big flower on the side of her head - it keeps changing. Also, her skirt is quite long up until the time the crocodile is after Bob Hope in the pond. But in the next scene, her skirt is about thigh-high.
As George and Harold rush the man in the white up to a higher platform to administer spot removal, the spot on his jacket miraculously has moved three inches down his lapel and the admiring audience of natives has changed behind them.
Although the ships' wheels are roped to the rudder and affixed to the deck strongly enough to withstand a storm, when their boat hit the rock, the wheel mounting falls to the side, clearly not attached to anything.