Pola is an acronym for "Pierre ou les ambiguites," the French translation of the title of the Herman Melville novel on which the film is based.
The "X" in the title represents the number of drafts the script went through.
Along with Annette (2021), it's the only film in which Leos Carax didn't cast his star Denis Lavant.
The sex acts between Guillaume Depardieu (Pierre) and Yekaterina Golubeva (Isabelle) are not simulated. However, body stand-ins were used for the most explicit parts.