Continuity mistake: In the first scene of their "training" for the big mission, the text "Somewhere near Galveston, TX" shows up as a subtitle on the screen. As it does this, there is a nice, dark aerial shot of mountainous terrain which is supposedly to hide the troops from any outsiders. The problem is, there are no mountains within hundreds of miles of the Island of Galveston. The whole terrain in this area is so flat that you can practically see from one side of the island to the other.
Continuity mistake: In the middle of the movie, the team of Americans get their truck-load of weapons confiscated by the Vietnamese government. As you watch over Gene Hackman's shoulder, you will see and hear the same truck get closed up and pull away several times.