Dangerverse/Shout-Out

• Monty Python is cited most often, but Star Wars, Star Trek, Chronicles of Narnia, Lord of the Rings are also referenced (Aletha quotes the latter when protecting Sirius from a dementor.) There is even an Animorphs reference, several references to Mel Brooks films, more than a few to various musicals, and a notable allusion to Calvin and Hobbes. There are also numerous nods to the original canon.
• Living With Danger ends with a reworked line from Philosopher's Stone.

They all disappeared as the train rounded the corner. Harry felt a great leap of excitement, but there was a little tinge of sadness to it. He knew what he was going to--but it couldn't be better than what he was leaving behind. (Living with Danger)
Harry watched the girl and her mother disappear as the train rounded the corner. Houses flashed past the window. Harry felt a great leap of excitement. He didn't know what he was going to--but it had to be better than what he was leaving behind. (Philosopher's Stone)

• The Bard of Avon is alluded to and even quoted on numerous occasions. One scene in Living with Danger centers around a reading of A Midsummer Night's Dream, and several titles are also shout-outs.
• Additionally, yes, the username the author uses on most fanfic sites is an Incredibles reference.
• In chapter 106 of Be Careful, Snape quotes The Chronicles of Narnia.

Snape: "'Further up and further in'?"
Lily (approvingly): "Exactly."