Revealing mistake: Thelma and Louise in one scene are driving at a very high speed with Brad Pitt in the backseat wearing a cowboy hat that never flies off, much less even moves with the wind.
Visible crew/equipment: In the scene where Thelma & Louise pass the tanker for the last time, before they blow it up, there appears to be an image of a man visible twice near the bottom of the tanker, just before the tanker cab is shown.
Audio problem: When Thelma approaches the Highway Patrolman's window you can hear her cocking the revolver she then points at his head, but the revolver remains visibly uncocked.
Chosen answer: It's just as you said; he was telling the others to hold their fire. He had no idea that they were going to drive off the cliff; his reaction was evidence of this.
zendaddy621