But Kline wasn't the least bit self-conscious, even when he pulled up alongside acting great Jeremy Irons and exchanged surprised greetings.
Kline was wearing tattered charity shop attire for his eccentric Henry Harrison character. Further, other than a mild-looking passenger in the front seat (Paul Dano), there was no outward sign of shooting a movie since the crew was crouching in the backseat.
"They were having this conversation," recalled co-director Robert Pulcini. "And there was no acknowledgment that Kevin was actually shooting a movie."
When the light changed, Kevin gave a wave to his friend and was off down the street in his clunker. Not even thinking about it.
When PopcornBiz reminded the exquisitely attired real-life Kline about the scene, he seemed to make a mental note that he owed Irons an explanatory phone call.
'"Oh God," he said. "I never even thought of that. He probably thinks I really have fallen onto hard times. I haven't seen him since."
What's worse, as he pulled away from the Irons on that fateful street corner, he stayed in character of snooty Henry Harrison and made a passing comment to his co-star Dano about the encounter.
"The light changed, and Kevin pulled off saying to Paul, 'Jeremy is a fellow Oscar winner. He's worth talking to,' " co-director Shari Springer Berman recalled. "And Paul shot right back, 'But he won for best actor not supporting actor.' "