musical movie continues to add A-list actors to its cast! Based on the Tony-nominated Broadway musical, Paramount Pictures' new film will see the return of some familiar faces and a host of new ones too. With Jon Hamm stepping into the role of Coach Carr, Busy Philipps confirmed in the role of Regina George's mom, and Jenna Fischer set to star as Cady Heron's mom, ET is taking a look at the cast — from newcomers like Reneé Rapp to the OG of the squad, Tina Fey.The star will play Coach Carr, who appears in the movie — as a sexual predator exposed in the Burn Book -- but was not featured in the original Broadway musical. This is far from Hamm's first collaboration with Fey, however. The actor received Emmy nominations for his guest appearances on and Philipps will step into Amy Poehler's shoes, playing Mrs.