The boy from the airport--SPOILERS
The way he totally freaked out when Don suggested their possible father/son relationship was just a tad over the top.
Not only does he run off immediately, but the little punk even keeps running full throttle when he's already a block away, as if it were possible for a fifty-something like Don to overtake him on foot. Come ON!
I didn't find this particular scene realistic, since Don was non-threatening throughout their entire conversation and posed the question in a low-key manner.
Otherwise a very good movie, one of those "thinking man's" flicks that doesn't spell everything out, leaving Don and the viewer alike wondering where he'll go from there.