When Pitt lands on boat, tucks his family into the bunks and goes to the command center, the movie shows various "goings on" from random angles, and during one of the angles, a scientist says "Around 5% of people infected don't show signs immediately".
I immediately leaned over and went "5% huh? Brad just drank a mouthful and is showing no signs huh? FORESHADOWING!", to which my friend laughed.
On the way home, after the film, he said "It's weird they made a point with the 5% thing but then it never came back up." and I said "I can only assume that was supposed to inform us of how it spread to different countries? Like, guy gets bit, gets on plane, flies home, days later turns and starts it up there? Just a guess, it wasn't really every explained. I really expected Brad to turn. Maybe all the AIDS he drank cured him?"