To hell with suspense: Oscar winners Julia Roberts and George Clooney joined James Corden and Gwen Stefani, making Wednesday’s “Carpool Karaoke” a special winner in its own right. Before the car fills up, the No Doubt co-founder and Late Late Show host chat aging secrets, light-speed lyrics, and the notorious eggplant emoji. Afterward, the quartet ponders the mystery of “Hollaback Girl” and valiantly tries to sing some Queen. God bless HOV lanes.