Audio problem: In the scene where the guys are looking at Olivia, talking about her nodding at Sebastian, Sebastian says something, then his phone rings. He continues mouthing something over the ringtone, but no sound is heard.
Audio problem: In the fight scene, in the bathroom, right as Viola jumps on Monique's back, Monique says "Get off me", the camera is looking right at her, but her mouth doesn't move when she says it for the first time.
Answer: Both Sebastian and Viola are supposed to be at this carnival so she has to keep changing to make "appearances" so it would appear they are both there.
edelian