Marianne says that either her or Powell's thumbprint is required to access a file, and since Powell is dead she will have to do it. But being dead does not stop someone from giving fingerprints: Jack had to cut one off a terrorist in Day 1. Also, later on in the season, Mitch Anderson cut off John Hansen's thumb in order to get access to the stealth fighter.
In the laundry when Jack is hanging in the vent upside down, he uses a small mirror to see where Behrooz and Navi are. But the reflection is wrong, it shows an image that he could only see if he was standing on the ground.
After Jack and his team leave the laundry room basement with Behrooz and Dina at 4:15:02, they go to commercial. At 4:19:13 they come back from commercial with a split-screen, and one of the shots shows Behrooz still in the laundry room.
When Audrey calls Raines on his cell phone, the display at his end identifies her as Audrey. But...she lost her own cell phone earlier when the terrorists kidnapped her and she's using a borrowed phone with a different (310) area code.