Revealing mistake: When Nick is being sucked out of the hole/cave, you can see the wires visible from his waist. (01:20:35)
Continuity mistake: When Amy is in the kitchen cleaning, she starts mopping the floor, then dancing with the mop held upside down. The mop starts out wet, but when she's dancing it's dry (either that or she would be getting dirty mop water in her face while the mop is being flung around).
Revealing mistake: In the scene where Amy lets Wayne know that breakfast is ready, she presses a button labeled breakfast. There are other items on the box, such as lunch, dinner, and phone. When they show the board flashing the word breakfast, you can see that the word breakfast is the only word the board can display between flashes.
Continuity mistake: When Nick is in the spoon, the milk around him turns green.
Audio problem: When Russ jumps from out behind the bush and says, "I say that ant is ours", his mouth doesn't move.
Continuity mistake: The hole in the window keeps changing size.
Character mistake: While pitching his shrinking machine to NASA Szalinski claims that reducing the size of a rocket's payload would result in "staggering" savings in the fuel required at takeoff. However, he makes it clear that his machine works by reducing the space between atoms, meaning that the shrunken object weighs the same as the original. Weight is the critical factor in calculating fuel consumption, not size. Anyone at NASA would pick up on that instantly.
Factual error: After their parents give up looking for the kids, there's a "time passing" scene showing the lit attic window from the outside of the house, in which the night grows lighter until it's morning of the next day. But the moon in the picture doesn't move. How can the moon stand still if time is passing?
Continuity mistake: When Amy walks toward Ron to offer him a truce, her hands are clean, but she somehow transfers mud to his hands when they shake.
Factual error: Nick says earthworms are dormant this time of year. In the summer? No way. Basic common sense says otherwise.
Continuity mistake: During the Cheerios scene, there's a shot of a huge green-screened spoon in front of Wayne, coming towards Nick, The spoon's position and movement are totally unrealistic to how Wayne would have moved it.
Revealing mistake: When Nick and Russ are riding the bee they turn completely green due to the chroma effect.
Continuity mistake: When the neighbour wakes up, the pillow behind him swaps from straight to skewed between angles.
Other mistake: When Amy hits the button to tell her dad that breakfast is ready, he tries to type "I'll be down in five minutes." However, the message on the strip of paper says "I'll be down in five mimmicks." Amy says, "Typing with his gloves on again." Even if someone was typing with their gloves on, the blatant misspelling would not happen.
Visible crew/equipment: Before the neighbors enter the house and get shrunk, all the film crew and a boom mic are reflected on Nick's glasses.
Visible crew/equipment: When the neighbors are shooing the cops out, the husband opens the door. As he does the reflection of a crew member in the door glass.
Continuity mistake: When Russ falls off the ant, the grass he lands on bounces up revealing the crash mat underneath.
Continuity mistake: When the kids open the waste bag, Nick steps forward, in between two kids, with about 10 centimeters between each. When the angle changes to Amy, Nick is jammed between the kids.
Visible crew/equipment: Stage lights are reflected in Nick's glasses before Russ yells "I say that ant is ours."
Continuity mistake: After all the kids have been shrunk, the nail on the floor swaps from laying between two planks to just one.
Answer: More along the lines of a serious health problem related to her "plumbing".
Greg Dwyer