The Voice: The Movie? Mark Ruffalo and Keira Knightley musical drama Can a Song Save Your Life? had already added Adam Levine as Knightley's no-good ex, and today, Levine's chair-turning compatriot Cee Lo Green joined the cast as well, playing a successful hip-hop star named Troublegum. Christina Aguilera is pursing her lips and voicing her limited congratulations. Blake Shelton is still waiting on his Hatfields and McCoys 2 callback.