Continuity: Selena parks her car close to the entrance, but in the next shot the car has moved 12 feet to the right.

Visible crew/equipment: 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 an umbrella-like structure used for lighting.

Continuity: When Selena holds on to the fridge door an American flag appears and disappears between shots.

Continuity: Supergirl lands the colliding car in a shadowy place but a couple seconds later the shadow is completely gone.

Revealing: In the castle, while Bianca says "I think I'll be going", the glass on the mirror has wrinkles, revealing it's a piece of aluminium foil.

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.

Revealing: When Supergirl flies through the window to fight the invisible monster, half of the screen shows her jumping in a school uniform and the other half exiting with the Supergirl outfit. Watch closely and you'll notice that her halves don't match, giving the sense that she is missing part of her body.