At approximately 20 minutes in, the mole uses a bump key to access a room.
Goof: Arthur Manchester and Tom Mason reminisce about "Boston College, History Department, Maloney Hall," and how Tom always sat in an aisle seat but "never missed a lecture." While Maloney Hall houses the administrative offices of the Boston College history department, none of its rooms are big enough to serve as lecture halls and, as of 2012, classes in that building are quite rare.
Molon Labe is an ancient Greek phrase, it was said by king Leonidas of Sparta to the Perses king when asked to surrender his troops. The most readily used English translation is "Come and take them."
At the very end of the episode, we can see that Weaver's rifle strap is released.
Pope makes a comment about Radio Free Europe, referencing the radio that Matt is using. Radio Free Europe was created after World War II to deliver information into the Eastern Bloc countries controlled by the Soviet Union.
On Mike's gravestone, his last name is given as Thompson.
In the early scene in the lab where they are talking about heroin, Tom is holding a package. From one angle it's covered in tape. As the camera cuts back to the other side, the package is totally bare with no tape. As the camera cuts back and forth the tape magically appears and disappears on the package.