Selena starts to say that everything is history and turns around to say the world is hers. Right then the angle changes and cupboards appear on the right from nowhere. When the angle changes, the cupboards disappear.
When the redhead girl and her friend fall on the girl's bathroom, the girl on the far left is holding a multicolored towel with circles drawn on. A split second later the circles are there but the towel is white.
When Bianca says she is going to kill someone down at the DWP because they have turned off the water again the DWP only exists in the United Kindom even though the film is British made it is based in the United States so the phrase she used is incorrect.
In the "monster tractor" scene, Lucy bangs her head on the right hand side before being knocked unconscious [rather easily], however when Jimmy asks if she's alright, Lucy says "I think so, I hit my head", and rubs the left hand side of her head, indicating the side that was hurt.
the girl jogger in the dorm scene is seen initially wearing a red, white and blue sweatband but after the girl yells "Man on the floor" she is seen running into a dorm room wearing a dark green sweatband.
The tires sitting by the gas station during the construction machine running rampant sequence catch fire, yet there is no reason for then to have caught fire in the first place. All the sparks and fire were nowhere near the tires.
As Supergirl changes to Linda Lee for the first time, she puts her right foot behind the tree, then picks up her left foot to bring it in front of her right, but before her left foot is out of sight, her right foot emerges from behind the tree.
When Selena uses her magical powers to accelerate the fairground ride to super fast speed, the twinkling fairground lights in the background are also flashing much faster. They obviously played the tape back at high speed to achieve this.
During the fight with the Invisible Monster in front of the girls' school, Supergirl gets thrown towards the lamppost she later uses to defeat the monster. She is clearly 1 or 2 feet from the lamppost, yet she bounces like she hit it, and falls to the ground.
When the principal first introduces Linda Lee to her new room mate, Lucy Lane, there is a box of Frosted Flakes cereal standing upright on a table against the wall. Moments later, the box is on its side as Lucy walks over to clean off the bed.