Card rooms were illegal in Arizona (and maybe still are, unless on Indian territory). So Mickey, whoever he was, had his chips shipped to Winterhaven, which is just over the state line and a few miles from Yuma. There were a number of card rooms in Winterhaven, catering perhaps to Arizona travelers in search of a good hand. One more order would not arouse suspicion, Mickey merely came over, grabbed his chips and sneaked back into Yuma.

Only problem with this is that Mickey's Hangover is in SCOTTSDALE, Arizona. Or at least his menu is.

https://www.allmenus.com/az/scottsdale/5069-mickeys-hangover/menu/

So the ChipGuide still seems to be wrong!