While this is supposed to be the same hospital where Rick wakes up from his coma in tt1589921, the cafeteria where the walkers are held in _The Oath_ is on the 1st floor, and the cafeteria full of walkers in "Days Gone Bye" is on the 4th floor where Rick was in the Recovery Wing (his room number is 450). There are some other mistakes in the set dressing that show the crew did not create the same look in _The Oath_ that is in the original Walking Dead series. Regardless, this is supposed to be the same hospital that is in the original series, as is revealed at the end of _The Oath_ web series.
Paul breaks the board holding the cafeteria door closed, but it is undamaged in The Walking Dead: "Days Gone Bye"
In "Days Gone Bye", there were no trees by the hospital.
When Paul and Karina first arrive and meet Dr. Gale Macones in tt3093524 and tt3093588, they are on the 1st floor. In tt3093474, Karina is looking out the window at a walker *below* her, indicating she is on the 2nd floor; there is no scene showing them walking up stairs and Paul enters the room they're in soon after leaving the cafeteria.