Continuity mistake: Sam hires a personal chef, Sonia. When Carly, Sam and Freddie are sitting at the table and Spencer is talking to them, Sonia takes the blueberry muffins out of the oven and puts her oven mitts down. Next, Spencer starts walking away. Then Sonia is putting down her oven mitts again. There is no way she could pick up and put down her oven mitts that fast. (00:13:15)
Continuity mistake: When they have the first meeting with the techfoot people, Sam is eating a sandwich. Every time the shot goes back to her and Carly, the amount of the sandwich she has eaten changes. Sometimes there is a bite taken, and then the next time there isn't a bite taken out of it.
Character mistake: Freddie mentions that they had an audience of 355k which was the most they've ever got. But in the earlier episode of ISpy a Mean Teacher, they had an audience of over 500k.
Answer: In direction translation it means 'Mischievous Spirit'. 'Hob' as in HobGoblin means clown or prankster, and 'Knocker' was an old age term for Poltergeists in mines. Miners would often complain of hearing knocking sounds down mines when there was no-one else down there, hence 'Knocker'. It's not a regular English expression though.
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