When Xavier opens the gift from his dad, the skates he receives are all black. When Xavier skates in the final skate-off against Sweetness, his skates have clear colored stripes on the side.
Xavier breaks the passenger window in his dad's car. When he moves back to the front of the car, the window is shown intact.
When X talks to Naomi on her stairs, her ponytail repeatedly moves in front of her shoulder, then behind it.
When X and his little sister are in the bed, she clearly calls him Ezekiel, and not Xavier.
When Junior's pants are pulled down as he skates, Tootsie Roll skates off. The next shot shows Sweetness, Tootsie Roll, and another girl standing in a group.
Curtis listens to Donny Hathaway's "For All We Know". The album "Extension of a Man" does not include that song.
When X and his friends first go to Sweetwater's Roller rink Tori mentions "Emotion" by the Bee Gees, but in 1978 Emotion was performed by Samantha Sang. The song was written by Barry and Robin Gibbs, but it wasn't till much later the Bee Gee's released their version of this song.
The film, set in 1978, includes a lot of 1980s and 1990s slang.
The inkjet printer in the employment office didn't exist in 1978.
In the opening shots of skaters, one skater has light-up wheels, which were first manufactured long after 1978.
One shot of the Sweetwater Skate-Off includes a skater skating on a Sunlight skate frame, which was first produced in the 1980's.
A number of songs in the film, including "Bounce, Rock, Skate, Roll", "Le Freak", and "He's the Greatest Dancer," had not been released in the summer of 1978.