A dozen games into its first season, LAFC is tied for second in the Western Conference in victories, goals and points.
Vela left after the game to join Mexico's World Cup team ahead of Monday's friendly with Wales at the Rose Bowl and Ciman, selected to Belgium's provisional roster, will begin training with the national team next week.
Neither Vela, the team's leading scorer, nor Ciman, the team captain, has sat out a minute for LAFC this season.
After a brief video review, Elfath waved off the penalty and that proved to be costly when Mattocks headed in the tying goal 16 minutes later.