The dismantling of the vestibule in the Sheriff's office is interesting. In the pilot, the reception window in Lucy's office opens out into a windowed room or breezeway that separates her from the waiting area. This is gone in the series. In episode one, there is a very brief shot (as Cooper walks in) of a man with a tool belt and another with a ladder and an acetylene torch "disassembling" this feature from the building. It's always seemed strange to me that they thought to "explain" the absence of this vesitbule in such a low-key way. It's really easy to miss (kinda like the existence of the room in the first place).
The vestibule in the pilot.

The vestibule dismantled in ep1.