During the scene at the railroad where John Henry Irons chases after a thug, a broken down fence has graffiti that resembles the written alien language from Alien Nation: Alien Nation (1989). Kenneth Johnson, who directed this movie, also directed several Alien Nation TV movies.
Steel is a DC Comics character. In the comic book, he was directly inspired by Superman when the Man of Steel saved his life (both literal and metaphorically). Since then, John Henry Irons sports Superman's shield as a homage to KalEl. At the movie, the existence or not of Superman is not touched, but John is related to the last son of Krypton via his tattoo.