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.
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: 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: 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.