The Nice Guys star appeared on Thursday night's episode of The Tonight Show to promote the film and was too convincing when telling the truth during the segment.
The Box of Lies game involves a shelf of boxes containing never-before-seen objects which players then describe to each other through a small window without showing them the item. Taking turns, the players either lie or tell the truth about what's in the box while the other guesses.
Fallon and Crowe faced-off with a 1-1 score until the late night television host sensed Crowe was indeed telling the truth about a manipulated starfish. Other objects picked in the game included an adorned xylophone and everyday junk drawer.