The Kings overcame a 13-point deficit in the final 4 minutes.
McCallum missed a right-side jumper with 3 seconds left, Reggie Evans caught the ball behind the left side of the glass and put up a desperation shot that McCallum grabbed in front of the rim and dropped in the basket.
Jeremy Lin led Los Angeles (3-5) with 19 points and seven assists. Ed Davis added 15 points and 13 rebounds, Julius Randle had 12 points and nine rebounds, and Robert Sacre had 12 points. Kobe Bryant and Carlos Boozer sat out the game. They both made the trip, but were not courtside.
Kings: This was Sacramento's 11th trip to Las Vegas to play the Lakers in a preseason game since 2000. They are 7-5 against them in Las Vegas. The Kings finished the preseason traveling 17,972 miles, most on a two-game trip to China against Brooklyn.
Lakers: Ronnie Price left with a sore right knee 2:47 into the game. ... A win would have given Los Angeles a .500 preseason for the first time since 2010-11. This was the second time Los Angeles played at the MGM Grand Arena. Last year, the Lakers also hosted and lost to the Kings. Previously, the Lakers played almost annually at the Thomas & Mack Center.
Sacramento hosts Golden State on Wednesday night in the regular-season opener.
Los Angeles hosts Houston on Tuesday night to start the regular season.