The outside establishing shot of Spence's subway station shows it to be the Steinway Street G/R/V stop. However, the scenes inside of Spence in his token booth read "Queens Plaza" which is two stops away.
In the close-up of the window, there is a box of tissues, a canister of markers and other items sitting on the wicker basket. When Doug goes over to the window, the basket is clear on top.
As Doug gets into his car, you can see the garage door facing the front street. However, we have seen the inside of the garage many times and the doors face out to a back street.
In the last scene, Arthur walks through the turnstile without paying. The turnstile would not move if token or metro card is not inserted. The turnstiles do not seem to have any slot to insert token or swipe metro card. The slot would be located on top of turnstile.
The character played by actor Michael Lowry introduces himself to Doug as "Mike Haller". He later introduces himself to Carrie once again as "Mike Haller". This wording is confirmed through the closed captions of the episode. However, in the closing credits, the character is listed (with an incorrect last name) as "Mike Ross", and his wife is listed as "Debi Ross".
(at around 14 mins) When Carrie gets up if you look to the upper back wall at the ceiling level you will see the studio lighting and what looks like a stationary boom microphone.