The movie was made as the first feature of the Committee of the Four Knights, a group founded by four of Japan's greatest directors: Akira Kurosawa, Keisuke Kinoshita, Masaki Kobayashi and Kon Ichikawa. According to a interview with Ichikawa, they wanted their first picture to be a hit. When this film told a story deemed too depressing and was subsequently a failure with audiences, the group disbanded and never made another film. The movie's failure also contributed to Kurosawa's suicide attempt one year later.
The artwork used as the cover of the region-one Criterion Collection DVD is Akira Kurosawa's original artwork for the film.
The title is an onomatopoeic sound that a train makes as it travels over the tracks. Rokku-chan makes this sound as he drives his imaginary trolley through the slum neighborhood.
The drawings shown toward the end of the film weren't by Akira Kurosawa. He usually used his own paintings, but he didn't think they'd feel right or childish enough, so he had some children draw some paintings that are the ones ultimately shown in the finished picture.
Akira Kurosawa: [weather] The rainbow over the rain signifies the characters' dreams over their bleak lives.