13 Going On 30 (2004) - 3 major mistakes

Continuity: Towards the end of the film, when adult Mattie hands Jenna the dream house (rebuilt) he had made for her 13th birthday years ago, there is hardly any "wishing dust" on its roof. However, moments later, when Jenna walks outside and sits on her front porch, there is plenty of "wishing dust" all over the roof of the toy house now.

Continuity: In her apartment Jenna walks out into the hallway, looks at herself in the mirror and stumbles backwards over the shelf behind her. There is a short stack of magazines on that shelf, yet when Jenna looks at herself in the mirror the stack of magazines is at least three times as high in the reflection.

Continuity: When the six girls arrive for the party, in the first shot Tom-Tom tosses her blue jacket, then the second girl lays her red jacket and the third girl starts to put her pink jacket into Jenna's arms. Yet, at the start of the next shot facing Jenna, she holds only the blue jacket, since the red jacket is gone, the pink jacket is placed in Jenna's arms on top of the blue jacket and then the red jacket is thrown into her arms from off camera, before the rest of the girls dump their jackets into her arms. Then in Jenna's close-up, the jackets are positioned very differently in her arms.