Audio problem: During the fight with the Scoleri Brothers, Egon warns doctor Stantz about the sudden apparition of the ghost coming through the wall. He yells "Behind you, Raaay!", but in the close-up Harold Ramis' mouth is not uttering "Behind you." (00:35:50)
Audio problem: Dana shows up at Peter's door with poor little Oscar desperately crying after the bathtub misadventures. Is he really crying though? Sigourney Weaver does her best to hold the baby close to her and away from the camera, that shoots the scene cutting off above the mouth level. His body language is composed though, and for one moment (when Dana says "this pink goo everywhere" his mouth pops in frame and it is closed. (00:46:20)
Answer: Because she knew Peter would want to get involved. They didn't part on good terms and she hadn't spoken to him since her marriage. She just thought it would be awkward to see him again.
Bishop73