At the beginning, in the Petrie kitchen, Sally and Buddy are sitting at the table next to each other with her left arm on his shoulder except for one shot in the middle when Buddy is standing up.
Rob is visiting Mexico on a three day pass, which means he is off duty. There is no reason he needed to wear his Army uniform the whole time, especially considering the fact that being uncomfortable and hot was a plot point.
Sally asks Buddy if he's ever heard of Opelaika, GA. Opelaika is in Alabama.
The door to the Mexican hotel room comes off it's hinges when Rob opens it.
Anchor, Texas, is in Brazoria County, near Houston. Dust storms are rare, and it's far more than 8 miles to the Mexican border.
In the 5th season, during a flashback Rob is on his honeymoon - His Army rank indicates he is a Sgt E-5. Yet before Rob was married, his rank was Sgt First Class E-7. E-5 is lower than E-7.