Tamsin West (who portrayed Linda Twist in the first series) performed the theme song.
The lighthouse that the Twist family lives in is an actual lighthouse. It's called the Historic Split Point Lighthouse and can be found on the Great Ocean Road.
Rik Mayall saw some episodes of the first season, became a fan and had expressed interest in a guest spot. So the episode Quivering Heap was written and the role of the punk ghost was written with him in mind, but Mayall couldn't get authorization to work in Australia, so had to be cast with someone else.
Richard Moir was replaced by Andrew S. Gilbert in the third and fourth series due to Parkinson's disease.
The schools that the kids go to is actually shot in Williamstown. It's about an 1-2 hours from the Historic Split Point Lighthouse.