20 Things You Didn't Know About Zodiac

4. Dermot Mulroney Had To Wear A Fat Suit For His Role

Dermot Mulroney appears for a few scenes as Captain Marty Lee, and if you assumed that he achieved that slightly doughy gut the old-fashioned way by chugging a few cases of Häagen-Dazs, think again.

Fincher took one look at Mulroney and decided that he looked too fit to convincingly play the real Lee, who had a less-defined physique.

And so, Mulroney was fitted out with a "fat suit" - though if we're being honest, Mulroney still looks pretty good, so a "pudge suit" is probably more accurate.

Given Fincher's infamous exactitude, the fact he didn't ask the actor to gain the pounds the hard way is practically miraculous.