There are several scenes where it appears the actors are waiting for their cues before they start talking; most notably when the Inspector calls them all into the room to recreate the seance.
It isn't a "goof" that the actors seem to be waiting for their cues before they start acting: many of the earliest MGM talkies employed a technique of long lingering inactive moments at the beginning and ending of reels, which apparently were supposed to take the place of leader when they changed over, perhaps accommodating the Vitaphone print versions. Years ago, when these titles appeared on TV, they didn't do that, so maybe Movietone versions were more succinctly edited.