Hired gun from Chicago, Charlie Steuben, is waiting in his hotel room for Ness to back off his tight surveillance. Steuben is throwing darts at a hand-drawn target on his door. Just before he tells his girl to leave, he throws a dart that sticks near the edge of the third ring from the center. As the girl leaves, he throws another dart but the first dart on the door is now just outside the bulls-eye center. The second dart hits near it so that both darts are now at the bulls eye when the scene ends.
When Nicky jumps on Eliot Ness and attacks him with a knife, the knife bends and wobbles, revealing the "blade" to be made of rubber.