Continuity: Supergirl's bracelet changes hands during the "Chicago Lights" sequence.
Revealing mistakes: 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.
Continuity: Supergirl positions her body twice in the flying ballet.
Continuity: In the "super showdown" scene, Supergirl reaches for the poles twice
Continuity: The jogger in the first dorm scene runs through the glass doors twice.
Crew or equipment visible: Crane used for flying shadow cast on the school building when Supergirl flies up and hits the invisible monster.
Revealing mistakes: When the invisible monster crushes Supergirl against a steel door, she flies to fight him and the wires holding her are visible.
Revealing mistakes: 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.
Continuity: When Selena is holding the glass champagne and says "I can't wait 'till the world is mine", from a back shot her finger is below liquid level, in the following shot it is above it.
Continuity: At the beginning of the movie, Selena drives her car to the right side of the house. When the shot changes, the car is several feet further back and is now heading across the front of the entrance.
Continuity: Selena's friend places the bottle of milk on the center of the burning chicken to extinguish it. When the angle changes the bottle is on the left side of the chicken.
Continuity: When at home, Selena says that the world is at her wish and looks down at the bronze sculpture which she is holding close to her chin. In the following angle her hand swaps to stomach level.
Continuity: At Selena's picnic, the label of the champagne keeps turning to face the camera.
Continuity: While Selena is burning the chicken, in the close up shot big flames come out, but a split second later, from a different angle, there's just smoke.
Revealing mistakes: When Supergirl is flying at super speed, the cars from the green-screen movie are also sped up.
Continuity: 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.
Crew or equipment visible: When Selena visits the school, there's a tube reflected on her window. When her car starts to move we see it's part of a structure used for lighting.
Continuity: When Selena holds on to the fridge door, an American flag appears and disappears between shots.
Continuity: When Ethan enters Selena's house, Selena opens the fridge. Her position behind the door changes from being in the middle to the right of it between shots.
Revealing mistakes: When Supergirl is passing by the town, flying towards the mountain, she flies very close to the ground but no-one looks at her.
Continuity: When Supergirl visits the principal's office, he is holding the glass down, close to the medicine bottle. When the angle changes, the glass is up without him having raised it.
Revealing mistakes: After Supergirl lands on Earth, she flies very close to a lake, but she doesn't have a reflection in the water.
Continuity: When the truck crushes the red car, the woman with the trolley makes a right to protect herself. When the angle changes she repeats the previous movement.
Continuity: When Ethan falls unconscious on the couch, his arm is close to his face. In the following shot it has moved down.
Continuity: At Selena's party, while Nigel is talking to the blonde girl, the green straw in his cocktail moves around between shots.
Revealing mistakes: In the castle, when Bianca says "I think I'll be going", the glass on the mirror has wrinkles, revealing that it's not glass.
Revealing mistakes: When Selena breaks the brick wall, the concrete holding it flutters, revealing it's a mere brown piece of fabric.
Continuity: The mirror in the castle changes to transparent glass when Supergirl flies through it. After the vortex swallows Selena and Bianca, it turns back into a mirror.
Continuity: Supergirl crushes a rock and gets dirt all over the sleeve of her suit. A second later dirt is gone and the suit is clean.
Continuity: Inside the girl's bathroom, when the red-haired girl comes running in with her friend, the towel is lying messy on the sink and a second later it's neatly folded.
Continuity: 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.
Continuity: After her fight with the invisible monster, Supergirl walks by the broken steel door she fell against, and it looks more crumpled and worn out than before.
Crew or equipment visible: Crane used for flying reflected in the window when Supergirl flies out.
Audio/visual unsynchronized: When Supergirl first arrives on Earth and crushes a rock with her fist, she has visible signs of dust on her costume. As she walks away, the dust on the costume is gone.
Revealing mistakes: 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.
Crew or equipment visible: During the "monster tractor" sequence, a boom operator is visible in the wrecked bar's mirror.
Continuity: 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.
Errors made by characters (possibly deliberate errors by the filmmakers): In the bulldozer scene, Supergirl puts water from the water tower on a gasoline fire. Putting water on a gasoline fire is a no-no!
Revealing mistakes: When Selena points at the fairground ride holding Linda and Ethan to make it speed up, you can see the ride through Selena's pointing finger (bad matte work).
Revealing mistakes: 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.