On the map of Sunnydale, the location of the demon is labeled Wilkins Grove, after Mayor Wilkins.
When Spike says "What's a word means 'glowing'... Gotta rhyme," it is an allusion to Fool for Love (2000) in which Spike, in a flashback as a human, was trying to think of a word that went with "gleaming" for a poem he was writing before being rejected by Cecily.
The site where Dawn finds information about Gnarl, "Demons, Demons, Demons", seems to be the same that Cordelia uses to find demons faster than Wesley, which has been used as a comedic joke several times in Angel (1999).
This line of Dawn's in which she points out that Willow could be the one to blame for her own problems, was cut due to length: "Instead everyone just keeps secrets, and suffers alone, and then we're supposed to be all sympathetic when they start ripping the skins off people or dragging their sisters to the basement! I may have some stuff to work through."
This is the first instance of Dawn fully participating in a "Scooby-hunt", taking the role of a backup/replacement for Giles in researching.