Prior to leaving Baltimore, when Hannibal is secured with straight jacket, mask & 2 wheel trolley, he is staring at a pen while Chilton is baiting him.
In Memphsis, Chilton looks for the pen but can't find it.
Later, Hanibal regurgitates the pin from the pen to use to free himself from the handcuffs.
So how did he get the pen, or at least the pin from it?
Did Barney assist him?