The school scenes are filmed at the school where Greg Davies actually used to work as a teacher; even the same classroom is featured.
The late Rik Mayall played the father of Greg Davies and the brother of Stephanie Cole, who replaced him in series two after his death. In fact, he was only 10 years older than Davies and 17 years younger than Cole.
During episode four, Greg hypnotises a community support officer to shout out his PIN number, 6079. This is actually the citizen number for the protagonist of 1984's Winston Smith.
The school featured during the show is St Clement Danes, near Chorleywood, featuring the Barbirolli Hall and the art department.