en.wikipedia.org/wiki/Mean_Streets

The article says Scorsese does not appear as a character in Mean Streets, but multiple film databases list him in the cast.

• Rotten Tomatoes' cast-and-crew page for Mean Streets lists "Martin Scorsese — Jimmy Shorts (uncredited)".
• Criterion's cast listing for the film also credits Martin Scorsese as Jimmy Shorts.

So while Scorsese does contribute voiceover narration, the claim that he does so without appearing as a character in the film is factually wrong.

This date conflates the film's festival premiere with its theatrical release.

• The AFI Catalog distinguishes between the two, listing "New York Film Festival screening: 2 Oct 1973" and "New York opening: 14 Oct 1973."
• TCM likewise says Mean Streets opened at the New York Film Festival and opened theatrically in New York a week later.
• Blu-ray.com also lists the U.S. release date as Oct 14, 1973.

So October 2, 1973 was the festival screening/premiere date, while the film's theatrical New York release was October 14, 1973.