The Girl with a Gift for Disaster - S3-E19
Revealing mistake: When the gas truck crashes against the blue car, it already has a dent on the door. After the crash, the dent disappears and the door gets fixed.
The Girl with a Gift for Disaster - S3-E19
Visible crew/equipment: Set lights are reflected on the bearded spy's glasses while inside the undercover plumbing van.
Answer: There is no logical reason. Any normal person would notice these type of absences. The show employs a "suspension of disbelief," which is a literary device where the movie audience or a book reader accepts that certain things are unreal for the sake of the story to be told. It is similar to no-one noticing that Clark Kent looks exactly like Superman because he wears glasses.
raywest ★