Continuity mistake: The white carnations in the vase on the piano (Higgin's study) move around from shot to shot during the scene immediately after the Embassy ball.
Visible crew/equipment: When Professor Higgins is having Eliza practice saying the letter H by blowing into a tube to make the flame waver, the paper she's holding is actually Rex Harrison's lines. Once the paper starts to burn and the camera angle changes, you can read them and it's practically all of his lines for the whole scene.
Factual error: In the Ascot racing scene, the actors' heads move from their left to right when the horses come to the winning line. From the stands at Ascot, the horses run clockwise around the track and would enter from right to left.
Visible crew/equipment: After Eliza has left Henry Higgins, he goes back home, turns on the record of Eliza's voice and sits down to listen. Behind him on the floor to the right, there is a shadow with quite a bit of movement, as if someone was nearby. There is no one else in the room; and it can't be Eliza's, because she is still outside the room, and hasn't approached the doorway yet.
Audio problem: In the song "I'm Getting Married in the Morning" Alfred steps on the pianist's hand. After this, is the piano keys he hits aren't the same as what we hear.
Continuity mistake: While Higgins is singing in the opening scene, he is sitting on a pillar and leaning over. He is shown leaning back up, but then the shot changes and he gets back up again.
Continuity mistake: In the song "I'm Getting Married in the Morning" there is a bottle of gin or something similar on the bar. When the bar-lady pours Alfred a drink, the bottle is close to the bar handles (those knob things in local pubs, they control the amount of beer pouring out), but as the song progresses the bottle gets further and further away from the bar-lady. DVD Showing.
Continuity mistake: When Prof Higgins orders Eliza to sit down, he points with his right hand; the next moment, from a different angle, he is lowering his left.
Continuity mistake: Watch Professor Higgins during the 'You Did It' number after the Embassy Ball. He sits down, taking off his shoes. At one point, he has a shoe in one hand and a cigar in the other. The cigar shoots to the other hand and the shoe disappears, then it goes back.
Continuity mistake: At the end of the song "Just An Ordinary Man," Rex Harrison races around the room switching on several separate phonograph players (which are all mechanical devices), producing a dissonant, squabbling ruckus. But, a moment later, as he utters the last line of the song, "I shall never let a woman in my life," he switches off the one phonograph nearest to him, and ALL the mechanical phonographs in the room stop playing instantly. (00:44:36)
Continuity mistake: When Eliza is singing 'I could have danced all night' her maids help her put on her nightdress. The sleeve on the left arm is left undone as she enters the bathroom and is washing her face. However as she exists the bathroom the sleeve can now be seen tied up.