When Ivan is playing ball with Debbie, he throws it outside through the window and it hits one of the bushes which starts to wobble.
Major Happy's costume has the musical notes on it back to front.The musical notes were stuck on the costume the night before by Raymond Childe's assistant.
The bells Major Happy plays do not correspond with the sounds they make. When he plays the scale, the large bells play high notes and the small bells play low notes when it should be vice-versa. Also in some places you can hear that the bells are made of plastic because the striking sound was not dubbed correctly.