William Shatner played Captain James T. Kirk in 'Star Trek,' an American science sci-fi seres created by Gene Roddenberry
David Carson was not the most accomplished feature film director. He only directed one minor film before Generations, so maybe he wasn't the best choice... but he did direct four episodes of TNG- including Yesterday's Enterprise- and four episodes of DS9 before filming Generations, so I think he had a pretty good understanding of what makes a Star Trek movie.
"Pasta." "Salsa for the nachos." "Nazis." All with that short "a as in cat" sound.
He was probably pretty pissed that he slipped and got called on it. Any actor working for a US market would know how odd it would sound south of the boarder.