Continuity mistake: When they are auditioning for the team, they stamp the fat kid's file "approved" under his photo parallel to the bottom edge. The camera cuts away and back to show the stamp at an angle with part of it on the photo itself. (00:13:40)
Deliberate mistake: When Zoom is moving the documents from the desk to the floor for Marsha to pick up, she quite blatantly catches him two or three times, but continues on with her business.
Audio problem: When Dr. Grant is explaining the plan to Larraby, when Larraby says "Is that our only option?", his mouth doesn't move.
Plot hole: When we see the Zenith Team playing softball, it's a scene taken from later in the movie. For one thing, Mr. Pibb is there, even though we don't meet him until the next scene. Second, they're in the room with the UFO, but we don't see that until later. Finally, Zoom's outfit is different than the last scene, but in the next scene he's wearing the same outfit.
Revealing mistake: Anytime we see the back of someone's head while they are talking, their mouths aren't moving.
Continuity mistake: When Summer says "Thanks for all your help, Captain," she takes the strap off her shoulder twice.
Continuity mistake: In the scene where the Princess and Houdini are running up the Zoom, Zoom is eating oatmeal. At one point, oatmeal falls on his chin, then the camera goes to Princess and she says, "You don't look like a superhero." Then the camera goes back to Zoom, the oatmeal's gone, and he reaches for a napkin. If he had wiped it off while she was talking, Zoom would have the napkin in his hand still.
Answer: She could be Cindy's Mom, who is video taping her daughter and not surprised by her powers. If not, she probably a government agent sent to keep tabs on her.
It's not Cindy's mom. The woman is after the boy is pulled up. Later Cindy's mom says "that's my princess" and it's a different lady (though a very similar outfit up top). I tried to see if there were other "out of place" people watching the other kids to see if government agents were watching them, but didn't see anyone.
Bishop73