I watched the film on DVD with my son and discussed it afterwards. He felt strongly about his interpretation, and said in support, “Didn’t you see the shot where [...]?” We went back to the point he was describing, and sure enough, there are about five frames that flash on the screen that explain the plot. My son’s visual acuity is far better than mine, and he saw this the first time through, whereas I missed it in three screenings.

I don’t want to ruin it by giving it away here, so if you’re desperate to know, send me email.