On first thoughts, either the panel behind the Golden Globe has mistakenly categorised it or there was some major screwups. On searching the news for why it was categorised as such, several things pop up.
Firstly, studio manipulating the film into a category that it has a chance to winning the award, Best Picture (Yay! who cares it is a comedy or musical category?!).
Secondly, other studios have been doing it! The other films in the same category, half are comedies, the other are not! No musicals at all anyway.
The winner and the nominees
The Martian
- The Big Short
- Joy
- Spy
- Trainwreck
From wiki
The Martian is a 2015 American science fiction film.
The Big Short is a 2015 American biographical comedy-drama film.
Joy is a 2015 American semi-biographical drama film.
Spy is a 2015 American action spy comedy film.
Trainwreck is a 2015 American romantic comedy film.
Even wiki disagrees that Martian is a comedy and definitely not a musical. The Big Short is about the market collapse. It probably needs a re-categorisating in wiki as well.
So this is a gerrymandering to prevent The Martian from pitting against the eventual Best Motion Picture The Revenant and preventing a loss. Well, every studio wants their films to pick up as much awards as possible and will not hesitate to do it.
Some articles on the categorisation!
http://www.dailymail.co.uk/tvshowbiz/article-3318139/Matt-Damon-s-Martian-considered-Comedy-Musical-HFPA-year-s-Golden-Globes.html
http://nypost.com/2015/12/10/the-golden-globes-think-the-martian-is-a-comedy/
http://www.latimes.com/entertainment/envelope/goldstandard/la-et-mn-golden-globes-martian-joy-trumbo-20151112-column.html
http://www.bustle.com/articles/129066-why-is-the-martian-a-comedy-at-the-golden-globes-the-matt-damon-flick-creates-nomination
http://www.cinemablend.com/new/Martian-Comedy-Now-Because-Golden-Globes-Gonna-Golden-Globe-94177.html
http://www.vanityfair.com/hollywood/2016/01/the-martian-wins-golden-globes-best-comedy