Carol Reed was one of the directors Charles Thomas Samuels spoke to when writing “Encountering Directors.” In their interview, Reed spoke about directing “The Third Man” and Welles.
According to Reed, Welles was “wonderful” and “marvelous” to work with. The only real difficulty he had with Welles was locking him down for a shooting time; the actor-director was keeping himself busy. “The Third Man” was (amusingly) one of three pictures Welles appeared in that were released in 1949, alongside “Black Magic” and “Prince of Foxes.” The year beforehand, he’d also directed and starred in a retelling of “Macbeth.”
Reed eventually relented on trying to lock Welles down for a specific portion of the shoot. As Reed explains it:
“So I said, ‘Look, we’re going on location five weeks. Any week — give us two days’ notice — we’ll be ready for you. And give me one week out of seven in the studio.’ He kept to it. He came straight off the train in Vienna one morning, and we did his first shot by nine o’clock […] He walked across the Prater, said two lines to Cotten, and then I said, ‘Go back to the hotel, have breakfast; we’re going into the sewers, and we’ll send for you.’ ‘Great! Wonderful!'”
Holly learns that Harry had been selling diluted penicillin to local hospitals. He reluctantly agrees to be the bait in a sting operation after police officer Major Calloway (Trevor Howard) shows Holly the horrors of what happened to children who were treated with Lime’s bad product. The chase to catch Lime takes him and his pursuers through the sewers of Vienna. According to Reed, this was the part of the shoot where Welles was most frustrated.