Is based (in part) on the life of the director's father, Miroslaw Zulawski, during the Second World War. Similarities include the birth of his first son during the occupation of Lwow, Poland (now L'viv, Ukraine), being a member of the Armia Krajowa (A.K., or Home Army, essentially the Polish underground), and working as a lice feeder at The Rudolf Weigl Institute.
In an interview with French film magazine, Positif, Zulawski stated that the "Third Part" in the film title was a private in-joke referring to what was generally seen at the time as "The Third Wave of Polish cinema."
Shares many parallels with Zulawski's later and most (in)famous film, Possession (1981), including having autobiographical elements of the director's life, actors playing multiple roles, doppelgangers, and religious themes.
Is considered the first (and probably the last) film about The Rudolf Weigl Institute.
When Trzecia czesc nocy was released in France following the success of L'important c'est d'amier (1975), many critics heralded Zulawski as ushering the 'third part of Polish Cinema'. However it was not to be: after the production of On The Silver Globe was shut down in 1978 Zulawski moved to Paris, where he remained until the fall of the Berlin Wall.