During the talent show the bass player's suit is green. At one shot towards the end, after they finish playing, his suit is blue. Then it turns green again.
At the talent show, during the performance by "The Legends of Brass", the guy in the gold turtleneck and the guy in the orange shirt keep switching positions.
When Faye and Guy are kissing at the end of the movie, the weather changes from an overcast-type lighting to a bright sunshine each time they change camera angles.
When the bass player visits Disneyland he rides in a Matterhorn car. In the beginning of the scene, he is in the rear of the front tandem bobsled, followed by Mickey, two marines, and Goofy in the rear tandem bobsled. At the end of the scene, he is in the front of the front tandem bobsled, Mickey and a marine are in the rear of the front tandem bobsled, and two marines and Goofy are in the rear tandem bobsled.
The ending lyrics of the song are sung differently when they record the song in the church and when they first hear it played on the radio. (it's the word "thing" in the next to last line of the song).
When leaving the Wisconsin State Fair and learning that their
record has hit #7 on the charts, Lenny asks if they get a gold record. Guy tells him they need to sell 500,000 copies. In 1964, 500,000 copies was the sales plateau for an LP to go Gold, but the sales plateau for singles was 1,000,000 copies. It was not until 1989 that the sales plateau for singles was lowered to 500,000 copies.
The three Marines who walk into the restaurant coffee shop have the Marine Corps eagle, globe, and anchor emblem on their shirt collars. This has never been part of the Marine uniform.
In regards to the three Marines wearing Marine Corps devices on their khaki blouses (never done), these same Marines are wearing pre-1959 enlisted rank insignia, which do not have the crossed rifles which would have been present on the post-1959 insignia of the movie's time period, which is 1964.
The Ford police car (aside from having incorrect blue and red roof beacons) is of the top (Galaxy) trim level. Public agencies bought on the basic trim level. In this case, it should have been a Ford Custom sedan with much less trim and chrome.
The movie is set in 1964. The band joins the Playtone state fair tour at the Ohio State Fair, which is depicted as being early in the tour and, judging by context of other events in the movie, early in the summer. In 1964, the Ohio State Fair did not begin until the end of August, and ran until the second week in September. The 1964 Wisconsin State Fair, depicted in the movie as coming later in the tour, was in reality in mid August, two weeks before the Ohio State Fair.
The TV show which seems to be Thunderbirds (1965), is actually its predecessor Fireball XL5 (1962), which had its American premiere in October 1963, and fits in the 1964 setting.
Lenny does not miss his cue at Villipiano's on "All My Dreams," he is making reference to the loud airplane flying over "the spaghetti place out by the airport" that they have gotten their first gig at.
When the photographer at Playtone says to Sol Syler "Saw you at Chasen's with Suzanne Pleshette," he raises the camera and takes a shot with it. His eye is nowhere near the viewfinder of the camera - it's behind the flashgun.
At the talent show, the girl who sells tickets (wearing a blue dress) can be seen dancing in front of Jimmy near the stage, but at the same time we can see her selling tickets near the entrance watching the band (with Chad) wearing a different dress. (Technically, she must be playing two different people.)
In the exterior shot of Villapiano's restaurant, the banner advertising The Oneders says there's a "TOO $ COVER." It should say "two."
When the Chantrellines are singing their song "Hold My Hand, Hold My Heart" they put their hand over the wrong part of their body where the heart is. The heart is located on the left side of the chest. The female singers put their hands on the right of their chest when they sing "hold my heart".
When they are making the movie on the beach Jimmy is looking really annoyed the entire time and no one cares.
When the Asian photographer is snapping shots at the Playtone reception, he's holding the camera in a vertical position even though the group is clearly horizontal.
Guy Paterson's father uses a remote to set the TV channel/volume to watch the Wonders. The early remote controls for television went into production in the late 1970s and early 1980s.
A character states that they'll have to sell 500,000 copies of their single to get a gold record. In 1964 it still required 1,000,000 singles sold to qualify for a gold single record by the R.I.A.A.. It wasn't until 1976 that this was changed to 500,000.
The movie is set in 1964. However in the studio scene near the end of the movie, one of the Fender guitar amplifiers is a Silverface model. The Silverface models were introduced in 1968.
When The Wonders perform on a circular stage mocked up to look like the record of That Thing You Do, the "label" on the record has a copyright notice at the bottom. This notice has the C in a circle followed by the year and Playtone Records. The problems with this are (1) recordings could not be copyrighted in the U.S. until 1972, and (2) after they were made copyrightable, the correct mark for a "phonograph recording" copyright was a P (or more correctly, a record should bear both a P and a C). Prior to 1972, the label art was the only copyrightable portion of a record so the records (or to be more specific... the 45rpm singles) bore either no notice at all or a notice bearing the words "All Rights Reserved." The same label is on the record held up by The Wonders in the photo shoot at Playtone Records.
Although set in 1964, the panorama shot of LA shows Sammy Davis Jr playing the Hollywood Bowl which he did on 10/5/1963 as listed on Setlist.
The cymbals in the drumkit bear the name "Sabian," a brand that did not exist in the 1960s.
When Uncle Bob is recording the Wonders, the sound and the visual of the hand claps are out of sync.
(At 1:50:30; Director's Cut) When Guy is running in late to the group's rehearsal for their first appearance on TV, the steady-cams operator's legs are reflected in the water fountain (right after Guy picks up his sun glasses off the floor).
After the Wonders meet the Saul Siler, we can clearly see the camera at the start of the following shot.
After reading a Telemart ad, Guy's father says that he's not sure he wants to live in a country where you have to do business on Sunday. Pennsylvania "blue laws" in effect during the 1960s would have made it impossible for him or Telemart to do business on Sunday.
In the extended version, the movie showing on the TV at Guy's apartment is not Spartacus (1960) as he claimed, but The Vikings (1958).
In the recording studio, after Guy plays his solo "I am Spartacus," Del comes in. He says, "Let's play that Spartacus number again." Guy goes on to play something that bears no musical resemblance to the solo.
The Villapiano's banner announcing the Oneders' extended engagement is misspelled as "by poplar demand."