When Sherrie Christian walks outside after her fight with Drew Boley, her big hair has already flattened and is wet without having walked into the rain.
When Stacee is being interviewed his fingernails are clear. When he gets up to take a drink he has black nail polish on.
During Sherrie's "More Than Words", Drew adjusts the microphone and the scarf is already tied to it even before Lonny did the "sound check".
When Patricia is explaining to her husband about her "roommate" in the car, she is holding papers. There is a office clip holding the paper together. The metal flaps on the clip switch between being up and being down.
When Lonny is testing the mike for Drew, he puts the scarf on it. However, when they originally get on stage, the scarf is already on it.
West Hollywood, where the Sunset Strip is, has never been part of Los Angeles, so the mayor of LA has never had jurisdiction there.
The story is set in 1987 but the characters sing songs written after that year, including Warrant's 'Heaven' (1988), Extreme's 'More Than Words' (1990), Poison's 'Every Rose Has Its Thorn' (1988), and Skid Row's 'I Remember You' (1989). Within the movie's "musical" illusion of reality, these songs are meant to be representative of the mid-1980s-through-early-1990s era as a whole, since this film is a nostalgic fantasy representation of the era rather than a historically accurate recreation of a specific year. Keep in mind also that an important plot element is the notion that the song "Don't Stop Believin'" is written in 1987 by the fictitious Drew Boley, but in real life was written by Journey in 1981, and was already a well known song by 1987.
During Drew's first performance on stage in front of the crowd, Drew keeps switching the way he is holding the guitar. This is due to the mirror effect that is shown by the fact that the writing on his shirt also changes.
During the interview scene while they are singing "I Want to Know What Love Is", Stacie's chest tattoo changes sides from left, to right and then back to left. However, this is explained by being in front of a mirror.
At the end of the scene where Drew's band opens for Stacee Jaxx, you can clearly see that the microphone Drew is using is designed to be used with a cord, yet it has no cord plugged into it.
Julianne Hough's belly button ring hole is hidden with makeup for most of the movie, but is visible is some scenes.
When Patricia and Mike Whitmore are in the limo talking about the Bourbon Club not paying taxes, they drive past an upside down car accident scene. After she says "They're broke", the camera cuts to him and when the camera goes back to her the scene is out her window.
Drew is seen walking with a foam hard case for his guitar. However, this type of guitar protection wasn't introduced until the 21st Century.
At the record store, one of the walls has a spread of Iron Maiden's 1986 album "Somewhere in Time" on it. The artwork featured is the artwork from the 1998 CD remaster; the artwork that the album had until then had the band's name and album title displayed much smaller and to the top left corner.
In the middle of the film, there's a post-1990 Lincoln Town Car.
At one point outside the Bourbon Club, a 1995 Chrysler LeBaron convertible (the sleeker model without the hidden headlights) is visible.