When Mrs. Hadley, Mr. Fulton, and Mrs. Fitzgerald leave at the end, they walk out of the house (closing the door behind them) twice.
When Pat goes to turn out the light in a drunken Ted's room, the window in the background is completely dark. When the light in the room goes out, it takes a beat before the light coming through the window is turned on.
When Stella goes to see Elliot at the Muntions Building, the view from his office window is of the Capitol Building and it is very close. This is not remotely possible. The Muntions Building was built on Constitution Avenue on the Mall between the Lincoln Memorial and the Washington Monument--roughly where the Vietnam Memorial now stands. In addition, the similar Main Navy Building stood between the Muntions Building and the Capitol.