Mark Wahlberg ceased his famous fanatical training regime and deliberately put on a significant amount of weight for this role.
Mark Wahlberg explained during an interview that he received a kind letter from a Muslim woman who accidentally entered this film in theaters mistaking it for Uncharted (2022). However, she loved the film finding it to be extremely beautiful and uplifting, and thanked him for making it, explaining that the way Stuart Long's relationship with and belief in God was very similar to her spiritual beliefs, which made Wahlberg very happy.
The barfly that speaks to Stu before his crash is implied to be the voice, or a messenger, of God.