Revealing mistake: In the tea party on the ceiling scene when Mary takes out her watch, watch closely, she doesn't take it from behind her jacket. When she seems to reach behind her jacket it just appears in her hand. When she puts it back she reaches behind her jacket again, but it just disappears just before she puts her hand back there.
Revealing mistake: In the scene with the queue of Nannies, and the chimneytop scenes, the wires holding the actors can be seen clearly.
Audio problem: During the Spoonful of Sugar song Mary stands in front of a mirror and sings along with her reflection. Her reflection sings "they find." but the mouth movements do not match. (00:33:30)
Revealing mistake: When Mary is taking the things out of her bag when she arrives, she takes out a large floor lamp. You can see the lamp's post coming up through the bag and the table as she pulls it out.
Continuity mistake: When Mary Poppins first enters the nursery and Jane apologies for it being a mess, the rocking horse is upright. When Mary starts singing a few minutes later, the rocking horse is now on its side and leaning against the white chair.
Audio problem: In the French, German and Spanish version, in the song Supercalifragilisticexpialidocious, before Mary Poppins says the word backward. While Mary and Bert sing in the dubbed version, in these three languages, you can hear the English version in the background. You can hear it louder in the French version.
Continuity mistake: When Mary Poppins starts to read the "qualifications", the paper she reads from is whole, with no kind of indication that it had ever been torn. After a quick cut to George and back to the paper, the closeup of the paper reveals the lines where it was torn. Also in this scene, when she comes in, she has white gloves on. In the closeup on the paper, the gloves are gray, and a few shots later, they're white again.
Suggested correction: According to the 40th anniversary DVD special feature "Poppins Fun Facts", it is just the lighting that make her gloves appear gray/black. They are, in fact, white the entire time.
Continuity mistake: When Mary and Bert are sitting down at the table, the penguin waiters place in front of them a placemat with a knife and fork on it. When we see Bert dancing with the penguins a little later on, the placemats and knives and forks have all disappeared.
Continuity mistake: As Banks realises what the phone call is about, Bert is picking up the last brush. A moment later, he picks it up again.
Revealing mistake: As the squirrels play around Bert and Mary, the background can be seen through their tails. (00:45:25)
Continuity mistake: When Mary holds up the paper, it appears whole, but in close up, the places where it was torn are visible, then whole again.
Visible crew/equipment: When the maid first opens the door to Mary Poppins, you can see a shadow of something, presumably the camera, on the maid's left shoulder until she steps right.
Other mistake: As Admiral Boom's assistant is loading the cannon a third time, he puts the red rocket in nose first rather than stick first.
Other mistake: After Bert and the others dancing on a railing that should have moved, as it did when they jumped off, three sweeps walk back and forth on their hands over the street between buildings. After dropping to only their toes to hold them up, you see them drop all the way down, then stand, where there was no surface in sight to do that on.
Visible crew/equipment: As Mary walks back to sit down the shadow of the camera is on her back.
Revealing mistake: As the sweeps dance and jump from building to building, the edges of the matted in street that hides the sound stage floor is easily discernible.
Revealing mistake: In the scene with the three chimneys, the sweep coming out of the middle chimney can be seen actually coming up from behind it, as his arms going up are visible.
Visible crew/equipment: As all the sweeps come out of the chimneys, the wires holding them are visible.
Visible crew/equipment: As Mary Poppins gets to the top of her exit from the chimney, the wires holding her are visible. And as Bert lands, his wires are visible.
Continuity mistake: As the Penguins answer the call, and are setting up the table, Bert is laughing and leaning in, and a second later, he is upright and all the way back in the chair.
