At the dinner ceremony where Spawn attacks Wynn and kills Church, you can see a red-headed woman in a blue gown walking among the patrons in the beginning of the scene. The camera focuses on her briefly, but for a reason - look at her earrings. They are Spawn insignia. This is a reference to the angel Hellspawn hunter Angela, who wears those same insignia in the comics as trophies of her victories over previous Hellspawn. Very clever reference.
In the scene where the clown is disguised as Wanda Simmons and Jason Wynn kills her in front of Spawn. After Clown looks like himself again he tell spawn that he hoped that Spawn would have killed Jason and start the apocalypse now and this was said right in front of Jason. Apocalypse now is a movie starring Martin Sheen who played Jason Wynn in Spawn.