The director's cameo?
Watching the Kino 2008 DVD of TAC, I believe I see a cameo appearance by this movie's famous director, D.W. Griffith.
At the beginning of the garden party sequence (at 00:15:24), a lanky man in a dark suit is seen talking with a group of women at the party on the left side of the screen. A momentary glimpse of his face appears. He then moves awkwardly, as he has been described in his biography doing in his earlier (unsuccessful) attempt at a stage-acting career (The Birth of a Nation).
What do you think? Is that he?
E pluribus unum