Continuity mistake: When Alice does flips to try and get on to the back porch of the house, her hair is different after she turns around to walk towards the door.
Continuity mistake: When the luggage goes through the scanner at the start of the movie the bad guys put their toy car on the belt followed by a brown bag. Scene then cuts to the old woman, and she picks up the bag which is the same bag as the bad guys', followed by a blue one. When the bad guy pick their bags up it's still in order they put it on, nothing swapped.
Character mistake: When Jernigan chases the car, he tells the team, "It's heading south on Adams." The toy car then turns left, which means that the car should be heading east. However, Jernigan tells the team that the car is headed west.
Revealing mistake: When Alex is walking back from Mrs Hess' after shovelling her drive, you can see the "crooks'" car lights waiting for their Q to enter the street in the top left. (00:10:10)
Character mistake: In the opening scene where Olek Krupa is looking at flight departures at San Francisco Airport, you can briefly see two entries that say "San Frnsicso." (00:05:30)
Answer: It was Jernigan who thought there was a woman in the shower and he couldn't take the risk that if it was a woman, that she would eventually get out and see intruders in the house and call for the police. The only option open to Jernigan would be to kill her so there'd be no witnesses.
No it was Beaupre who thought there was a woman in the house.
I've seen the movie and I can confirm that it was Jernigan who opened the shower curtain because he thought a woman was in the shower.