It made perfect sense that karaoke would play into the opening-night festivities for Universal’s musical-comedy “Pitch Perfect.”Held at the Cinerama Dome in Hollywood and Lure nightclub, Monday’s opening hit a high note as guests at the afterparty were treated to a live band that invited volunteers onstage to sing their favorite songs. Those braving the spotlight included cast members Anna Camp, Rebel Wilson and Anna Kendrick, who covered the Guns N’ Roses classic “Sweet Child o’ Mine.” Producer Max Handelman said the key to the pic was striking the right balance between the comedy and music. “We always looked at this as a comedy first and didn’t want something that sounded like ‘Glee’ but was only a little funny,” Handelman said. Helmer Jason Moore grew up watching John Hughes movies, which definitely made an impression. “The idea behind ‘The Breakfast Club’ was to undermine stereotypes and to have those characters rise above those stereotypes, and I hope this film has that essence too,” Moore said. Everyone agreed that on a set where people constantly broke into song, a little glee rubbed off on all. “I’m still singing ‘No Diggity’ in the shower,” Handelman said.