In the Dreams' version of "One Night Only", the girls' capes fall to the floor during the opening bars. After the next shot, they disappear.
During the "It's All Over/And I'm Telling You" scene, Effie's wig is wider on the sides. In many close-up insert shots, the sides of her wig are tighter.
Just before the gospel break of the "Steppin' to the Bad Side" number, a medium shot of the Dreamettes features Deena on the left, Lorrell in the middle, and Effie on the right. The shot immediately following is a long shot showing the full stage, with Effie now on the left, Deena in the middle, and Lorrell on the right.
During the Detroit Theater Talent show, Effie adjusts her wig while adjusting her outfit backstage. In the very next shot, her wig is perfectly in place.
During the success montage, the Dreams' "Dreamgirls" single is shown climbing up Billboard magazine's "Top LP's" albums chart, not its "Hot 100" singles chart.
In the montage, the song is #1 in its first week, but was also #8 the previous week.
When the Dreams are being televised in color, the TV cameras have color viewfinders. Studio color TV cameras usually have black and white viewfinders, which are actually small monitors.
The Dreams' success montage includes a picture of the trio standing on the Great Wall of China. The U.S. and China had no diplomatic relations from 1949 to 1971; Washington had ties with Taiwan instead. However, the two countries had numerous cultural contacts in the late 1960s. China wanted to improve relations with the U.S. because their relations with the U.S.S.R were growing strained. It's entirely possible that China would've invited a famous singing group like the Dreams to tour the country.
During "Steppin' to the Bad Side", tambourines appear just before the gospel break. It's part of the choreography, using an old stage and film musical technique.
Fluorescent floor tape for the actors' marks are visible in the tracking shot during the second verse of "And I Am Telling You I'm Not Going".
in the 1960's in a live stage show as in "Steppin To The Bad Side" the girls are all over the stage with no microphones, yet their voices are clearly heard.
When Effie is at the unemployment office the American flag is hung incorrectly. The stars should be in the upper left, not the upper right.
When Deena and the girls perform the disco version of 'One Night Only', the stage backdrop is made up of computerized moving head lights, which didn't exist at the time.
In a scene set in 1965, the Dreams and Curtis are in the studio during the 12th Street riots in Detroit (according to the archival footage), which began on July 23, 1967.
The Chicago NBC Tower, which opened in 1989, appears during the "Steppin' to the Bad Side" montage.
During a 1965 press conference, a photographer uses a Nikon camera that was introduced in the late 1980s.
The magazines in the montage following the Dreams' first performance are all dated 1964. The next shot shows a 737, which entered service in 1968, taking off.
The lip-sync is off during some verses of "It's All Over" and "And I Am Telling You I'm Not Going".
Near the end of "Dreamgirls," the audio sounds like the three women are singing the line "We'll be there", but Effie doesn't move her lips.
When Effie goes to the welfare office, the American flag hanging on the back wall is backwards. The blue field should be in the upper-left corner.