Fun facts!

The Annotated Pilgrim
The Annotated Pilgrim is a zine relased by O'Malley which discussed the making of Scott Pilgrim from Vol 1 to 2. It includes sketches, references and material from the volumes. It was apparently sold at the volume 4 launch party. The zine can be found here!
There's a live journal verison of The Annotated Pilgrim which includes more extras than the zine which I'll provide below. :3
Part 1 - Part 4
Part 2 - Part 5
Part 3 - Part 6

The font used for the Scott Pilgrim logo is called ‘SuperFly’

Knives’s friend Tamara wears a Kanye West shirt. Near the end of Vol. 4, Tamara is spotted wearing a pink shirt with Kanye West’s mascot, the dropout bear! In Vol 5 Bryan Lee O'Malley thanks Kanye West in the beginning! Also I did some digging in Bryan Lee O’Malley’s Tumblr where he answers a question regarding his favourite Kanye West song.
I found an article where the Chicago paper Redeye's "Pop Person of the Year" which features an illustration of Kanye West in the Scott Pilgrim art style. This was released in 2010 after Kanye West released his album MBDTF an era of Kanye notorious for the amount of controversies he was in including the MTV VMA incident with Taylor Swift. The article itself is short and it talks about the illustration with Bryan Lee O’Malley’s reaction to it (which I don't think he said or wrote himself 😭).

Kim and Lisa originally didn’t come from Scott Pilgrim! Kim and Lisa were the main characters for a previous webcomic Bryan Lee O’Malley did before Scott Pilgrim and Lost At Sea.
Only three comic strips were released and you can read them here!