Sylvester Stallone described the location of Tulsa, Oklahoma, with all its dusty weather and 103°-111° heat, as being "by-far, the roughest" filming location he had ever experienced.
Dwight also goes by the moniker, Cinque Stelle, which is Italian for Five Stars, as in a Five Star General, the rank of his namesake Dwight D. Eisenhower.
Ritchie Coster spoke in his character's (as he described it)"terrible" Irish accent throughout filming even when cameras were not rolling because he was afraid of losing it if he stopped.
Apart from the airport and a few exterior establishing shots, the lion's share of the series was filmed in Oklahoma City, not Tulsa.