Goofs

When Gwendolyn holds a match to light Cecily's cigarette, the cigarette is lit already. Also, Gwendolyn's match flame does not come close enough to the end of Cecily's cigarette to light it.

Gwendolen is shown driving a car out to Jack's country house. However, later in dialog with Cecily taken from the original play, she mentions having taken the train out. Later, Lady Bracknell mentions them both returning by train, which would have left the car in the country.

When Miss Prism opens Dr. Chasuble's portfolio, the second drawing from the top is partially folded, but when she examines it in the next shot, the drawing is neat and unbent in the stack.

During the song "Lady Come Down" Jack leans against a pillar at the foot of the stairs with one leg crossed in front of the other. The leg that is in front changes from left to right, and back to left again as the camera angle changes.

When Jack and Algy are picking flowers, and Gwendolen and Cecily ride through the woods sidesaddle, their legs change sides from the left (correct) to the right.

In the scene where Algy comes upon his servants playing music together, the banjo shown is a modern "bluegrass style" banjo with 5 strings and a resonator. At the time this movie was set, the banjo was a popular instrument, but it would have been the 4 string, open backed type.

During Cecily and Gwendolyn's outdoor tea, Cecily cuts a large slice of cake that is served to Gwendolyn and placed on the corner of the tea table. After the cake is cut, the scene clearly cuts ahead to the end of the tea. In the time that elapsed during this part of the scene, a servant easily could have come by and taken the plate explaining why in subsequent shots with both Cecily and Gwendolyn and later, when Jack and Algernon take the ladies' seats at the tea table, the cake and its plate are missing.

Jack's plaid tie was trademarked by Burberry in 1924.

When Algy is playing the piano for the 'Lady come down' song his hands are moving but the keys of the piano don't move.

(at around 59 mins) Cecily says that Ernest proposed to her only 10 minutes ago, but in her own imagination she and Ernest have been engaged for 3 months, so she would have the prior claim over Gwendolen.