There's a scene later in the movie where Bruno is nearly run over twice whilst crossing the street. This was absolutely unrehearsed - it was filmed on location and the two cars happened to pass by at that time.
The movie director Sergio Leone worked as an assistant for Vittorio De Sica during the filming of this movie. He also has a short appearance as one of the priests that are standing next to Bruno and Antonio during the rainstorm.
Even though Lamberto Maggiorani remained uncomfortable with the mechanics of filmmaking and acting, he nevertheless began to feel a merging of his own identity with that of his character Antonio. Vittorio De Sica later stated that Maggiorani "confessed to me that he had experienced this sensation, acutely and poignantly, in the last scene in the film: Antonio, in a moment of revolt against his cruel fate, attempts robbery and is arrested and maltreated in front of his son. When, through his tears, Lamberto Maggiorani felt his hand seized by little Staiola, it seemed to him that it really was his son who took his hand, and his tears became real tears of burning shame. In a few months of patient effort, I had brought this man to the point of being able to forget himself in his role and to enter fully into the sad story."
For his cast, Vittorio De Sica chose a factory fitter who had brought his son along for an audition as his male lead. His lead actress was a journalist who had approached him for an interview, while the young boy was filled by a child spotted in the crowd watching the filming.
Vittorio De Sica still hadn't found the ideal actor to play Bruno when filming began. It was while he was shooting the scene in which Antonio searches for his friend who can help him locate the bike that fate intervened. "I was telling Maggiorani something," he recalled, "when I turned around in annoyance at the onlookers who were crowding around me, and saw an odd-looking child with a round face, a big funny nose and wonderful lively eyes. Saint Gennaro has sent him to me, I thought. It was proof of the fact that everything was turning out right." And so little Enzo Staiola was hired on the spot to play Bruno.
Lianella Carell was a journalist who came to interview Vittorio De Sica when they were looking for someone to play the role of Maria, but, when De Sica saw her, he instantaneously decided that she would play Maria for the movie.
Vittorio De Sica's son Manuel recalled in an interview the filming of scenes in the Piazza Vittorio Emanuele: "...Papa told me about coming across, early in the morning, the director of photography of the film Carlo Montuori, completely frozen, clinging to his camera, devotedly waiting for the fleeting moment. He had stayed there in order to protect with his whole body the chassis (the magazine of film mounted on the back of the camera) from the rigours of the night. Dawn has a brief duration, and for this reason several days were needed to sew together long sequences which had cost many early forced awakenings for the entire troupe just to get a few minutes of footage...During the filming in Piazza Vittorio, he required the production secretary, Roberto Moretti, to stop the trams passing. Poor Moretti, who did not even have a permit to set up the tripod of the camera on the square, with great presence of mind disguised himself as a tram conductor, and began to redirect all the trams bursting with workers that happened to pass in proximity to the square. Before anyone guessed the reason for the existence of this man in the middle of the crossroads, the shooting was finished and Roberto arrested."
The film is frequently on critics' and directors' lists of the best films ever made. It was given an Academy Honorary Award in 1950, and, just four years after its release, was deemed the greatest film of all time by the magazine Sight & Sound's poll of filmmakers and critics in 1952. The film placed sixth as the greatest ever made in the latest directors poll, conducted in 2002.
Lamberto Maggiorani was very shy and embarrassed throughout the shooting as he had no actor training or would often become anxious when he couldn't do what Vittorio De Sica wanted him to do. The director, however, did not coddle him because he knew Maggiorani's real anxiety and nervousness before the camera would work well for his on-screen character. De Sica would later praise Maggiorani, saying "The way he moved, the way he sat down, his gestures with his hands hardened from work, the hands of a working man, not of an actor...I made him promise that after the film he would forget the cinema and would go back to his job." But during the filming, De Sica would still send a black limousine to pick Maggiorani up and bring him to the day's location.
Future Italian director Ettore Scola, who was only fifteen years old at the time, recalled passing the Piazza Vittorio whilst on his way to school one day and wondering why it was so deserted that time of day. He said, "...only a worker, a street sweeper and a child were crossing the street, going in the direction of the market. A low and strangely close voice, like that of a prompter amplified by a megaphone, reached the actors and the crowd gathered behind the barriers: 'More slowly, Lamberto. Let Gino go ahead. Enzo, keep behind Papa.' The whisper was coming from a small tower on top of which, in a little wooden armchair, was seated a gentleman wearing a hat, a scarf, and a camel hair coat."
It took careful planning and rehearsing to give the film its realistic look. Crowd scenes were meticulously staged and drilled, including one for which Vittorio De Sica hired 40 street vendors. The Roman fire department provided a "surprise" rainstorm for another scene. In addition, De Sica shot with as many as six cameras at once to get the untrained actors' spontaneous performances from several angles. Although the film looked like a documentary in places, the director's painstaking methods drove him over budget.