Amanda Seyfried was almost cast as Regina. Fortunately, director Mark Water's "fifth sense" kicked in and he realized she'd be better as Karen. (Source)

Amy Poehler (Mrs. George) taught Rajiv Surendra (Kevin Gnapoor) how to rap and even taught him some smooth (?) dance moves. (Source)

Rachel McAdams (Regina) is only seven years younger than her onscreen mom, Amy Poehler. Maybe that's why Mrs. George is so desperate to be Plastic.

Yeah, probably not. (Source)