This is the first episode of the series Lawrence Fletcher's parents appear.
This is one of three episodes which do not feature any of Phineas and Ferb's friends (Isabella, Baljeet and Buford). The other episodes are Toy to the World and Elementary, My Dear Stacy. This is to be expected since both this and the latter take place in England, and in Toy to the World the boys are spending more time supervising the factory.
Phineas: Grandpa Fletcher, we should have a medieval tournament, like the knights did in days of yore! We can have jousting, a catapult, and not bathe!
Grandpa Fletcher: Way ahead of you on the not bathing.
Doofenshmirtz: Perry the Platypus, your dragon robot is no match for my Queen Elizabeth the first... robot. Do you want to switch? Come on, be a sport!
Song: The Black Knight of Worstershire.
When they mention that a new version of Jane Eyre is in the making, they are refferig to the famous novel, Jane Eyre with the many adaptions to go along with it.
Title: A Hard Day's Knight
A take on the song, A Hard Day's Night by the Beatles.