Jay's gone through rehab and no longer does drugs (despite still dealing them); Jason Mewes also went to rehab prior to filming this movie (allegedly, Kevin Smith would not allow him to be in the movie unless he cleaned himself up). Unlike Jay, however, Mewes has not become a Christian, or at least not a devout one; this change in Jay's character is more than likely inspired by the events of Dogma.
Emma's hatred of New Jersey is apparently inspired by Jennifer Schwalbach Smith's own distaste for the state.
Randal's comment that after Dante leaves Elias will be his new best friend is a nod to Jeff Anderson's film Now You Know where he and Trevor Fehrman played best friends.
Actor-Shared Background: Jay's story of how he and Silent Bob finally sobered up parallels that of Jay's actor Jason Mewes, including being arrested for driving around with a deployed airbag.