Corrected entry: When Maggie, Lisa, Bart and Marge jump from the treehouse to the sandbox portal to escape the Springfield mob after them, no one of the mob sees the four jump in the sandbox despite that many were around the sandbox. They only notice Homer jump and get stuck initially. There would be no way for anyone to miss the other four Simpsons jump.
Sam Johnson
5th Sep 2007
Correction: This isn't really a mistake - they probably did see them, but they're only after Homer, not the rest of the family.
Sam Johnson