Authorities said the male lion tried to get into Harrah's Hotel and Casino on Friday morning.
Guests at the casino reported seeing the cat try to walk into the casino, but it couldn't figure out the revolving door, so it hit under an outdoor stage.
Wildlife officials were able to subdue the animal with a tranquilizer dart.
The groggy two-year-old male lion took his time returning to nature.
It stayed in the container for about three minutes before it finally poked its head out, looked around and took off.
Wildlife officials fitted the mountain lion with a GPS so that researchers can track its behavior.
Nevada Department of Wildlife spokesman Chris Healy told KCRA that although the behavior was typical of young cat--the equivalent of a "stupid teenager"--he still said the case was uncommon.
"I've been here 27 1/2 years and this one is new to me," Healy said. "We've seen mountain lions on the fringes of Reno before, but not in downtown Reno."
As numerous media outlets have reported, now they know they just can't "roulette" the chance of a lion in a casino.