Alias

Very subtle but when Marshall hugs Dixon near the end the song playing says, "here by my side an angel," and when he hugs Sloane - "here by my side the devil." The actual title of the song is Weapon by Matthrew Good.

Number 47: The hard drive that Sydney must find is in for repairs on level one, room 147.

Number 47: Marshall is being held in the storage room on the 47th floor.

An easily recognizable corridor has been used in at least 3 episodes which supposedly occur at different locations:
2x01 - The Enemy Walks In : Time: 30:56
2x06 - Salvation : Time: 22:20
2x11 - A Higher Echelon : Time: 37:59.

Why did Marshall turn back on Suit and Glasses at the end? He didn't seem to know that Sydney was about to rescue him. How could he put his mother's life at risk so blatantly? He knew that they would kill him and her.

What's the point of putting Jack's fingerprints on the wheel of the rental car he rented in Taipei? It was months ago that Jack rented the car - it would be more suspicious if there were clean copies of his fingerprints on the wheel - rental companies clean their cars, and rent them out to other people. There should be dozens of other customers' prints on the wheel, assuming there were any prints at all.