Other mistake: When YoYo drops Herman after the potion wears off, his wig flops up.
Other mistake: Herman's Dr.'s appointment is at 9am but the wall clock in the Dr.'s office shows the time at 9:33 or so.
Suggested correction: Most doctors keep patients waiting much longer than this. The clock should have read 9:45 at least.
Come Back, Little Googie - S1-E25
Other mistake: When Eddie's naughty little friend goes to shake hands with Herman they insert a quick close up of a hand buzzer in his hand, only it's obviously an adult's wrinkly hand.