Today’s game features an unusual (and so far unique) start time of 4:50 p.m. Why?

Fortunately, MLB’s Collective Bargaining Agreement is online in its entirety and provides the answer, in Article V(C) paragraph 8:

... beginning with the 2013 season, no Club shall be scheduled to play a road game starting after 5 P.M. if such game is a road game and is followed by a home off-day ...

The Marlins are definitely on the road today, and they definitely have an off-day tomorrow followed by a 10-day homestand. So, the last minute today’s game could have begun was 4:59 p.m. PT. The Dodgers are generously giving the Marlins a 9-minute head start.