But Spotlight ó an ode to the hard-nose, methodical work of a journalism increasingly seldom practiced ó took the nightís top honor despite winning only one other Oscar for McCarthy and Josh Singerís screenplay. Such a sparsely-awarded best picture winner hasnít happened since 1952ís The Greatest Show On Earth.
Doesn't the sentence need a comma after 'only one other Oscar'?
There is only one 'only one other Oscar', so the phrase modifying it should be non-restrictive, right?
The way it is written it seems that the film had already won an Oscar for 'McCarthy and Josh Singer's screenplay' and it won only another one.
Am I correct?
Yes, I'd put a comma there, for the reason you mention.