Patzer

During the dancing lesson that Dolly gives Barnaby, Irene and Minnie return from changing their clothes and Minnie Fay's dress alternates repeatedly from full-length to three-quarter-length until they all dance out the door.

When Horace Vandergelder is being shaved, the barber shaves once side of his face twice, removing all the lather both times.

When Dolly comes down stairs of Harmonia Gardens, her dress has a train that trails several steps behind her, but by time she reaches bottom, train has disappeared - a mid-scene alteration allegedly made necessary by Streisand's difficulty in dancing with the trailing gown.

The red-carpeted staircase at the Harmonia Gardens restaurant has brass carpet rods on each stair during all of the scenes prior to the arrival of Dolly Levi. When she arrives and they sing "Hello, Dolly," the carpet rods are gone.

When Horace is marching in the parade, Dolly approaches him to talk so he holds the sword upward on his right shoulder. Between cuts, when she talks about dinner at Harmonia Gardens, the sword disappears repeatedly.

There are several shots of the orchestra in the Harmonia Gardens during which no conductor can be seen, yet right before his duet with Streisand, Louis Armstrong suddenly appears conducting the orchestra before turning to join Dolly in singing. Later, he disappears once again.

Different lighting in between shots during the Dancing sequence in the hat shop while Dolly teaches dancing to Cornelius and Barnaby as Irene and Minnie watch, at the same time Minnie's dress cuts from full length to above-the-boots length.

Michael Crawford's natural English accent slips out several times.

Once the duet between Dolly and the bandleader (Louis Armstrong) is done and Dolly dances away with the waiters, as Louis waves goodbye a blonde dancer smacks him in the hand very noticeably.

All of the food and drinks on the waiters' trays are obviously glued on during the dance number at Harmonia Gardens.

During the parade the order of the various groups change position from time to time.

In the final wedding scene, Dolly comes down the hill dancing on a pathway/sidewalk that definitely is made of asphalt which was not around in 1890. Brick or stone would have been the usual material, but in a country location like this, dirt or gravel would have been used.

In the final scene when Dolly steps from the side walk onto the grass hurrying to be with Horace who is waiting for her on the church steps there isn't anything on the lake in the background until the very ending of the song after a couple of close-ups when they zoom out and 2 sailboats can be seen that wouldn't have had the time to get out on the lake as far as they are.

"Entr'acte" is incorrectly spelled "Entre'Acte"

When Irene and Minnie meet up with Cornelius and Barnaby at Harmonia Gardens they say "We're here" and "Hello" (in a two shot of Irene and Minnie respectively) they then switch to a two shot of Cornelius and Barnaby (when Barnaby tips his cap ) and Cornelius is behind Barnaby's left shoulder. Then the shot changes to a side group shot (where Cornelius kisses Irene's hand) but now his body has jumped a little in front of Barnaby's..

During opening credits, as Walter Matthau's name appears, a couple of wrecked modern automobiles (circa 1960s) can be seen dumped in foliage to right of railroad track.

During the opening credits, a scene shows the Train passing a boat on the river. The boat clearly has an exhaust funnel and is pumping out bilge water. The film is set in 1890, and diesel engines for boats didn't exist until 1897, and electric bilge pumps weren't common on many boats until the 1940s (the were more commonly used on large naval/merchant vessels).

During the opening sequence: When "Based On The Stage Play 'Hello Dolly' Produced by David Merrick and Book of Stage Play by Michael Stewart" comes on the screen, you can see in the background an interstate highway going around the base of the tall hill with cars whizzing by.

The Budweiser Clydesdales and beer wagon appear in the 14th street parade. They were not formed until 1933, well after the period in which Hello Dolly is set.

Modern electrical power transformers are visible on the utility poles in the Yonkers scenes.

During the "Hello Dolly" song at Harmonia Gardens towards the end of the movie, she's singing with Louis Armstrong, after they do their exaggerated "yeah..." she's supposed to sing "Dolly will never go away..." Her voice sings the word "will" in that phrase, but her mouth does not.

In the park during "It Only Takes a Moment," the group of bystanders starts to sing. There are only 9 people, and only 3 of them women, yet the chorus heard is clearly much bigger and much more female.

Yonkers is North of New York City, and both are on the East side of the Hudson River, . But in some aerial scenes of the train from New York City to Yonkers, the river is on the train's right side. A Southbound train was filmed.

In the opening number, Dolly boards a southbound train. Yonkers is north of New York.