When JB arrives in Hollywood he sees the Hollywood Sign and turns a looks right into the camera and gives a thumbs up sign, ostensibly to the audience. This is the only time in the film that the fourth wall is broken, I think. There are times when JB talks to himself and an exposition device, but that's something else.
It's not really the first time that happens. In "Top Secret" it also happens, and I'm sure I've seen other movies where the forth wall is broken, but I can't remember any other at the moment. If I do, I'll post again.
Sorry if I made any language mistake, I'm portuguese :) Greetings.
By the words "This is the only time in the film that the fourth wall is broken, I think", I'm only referring to Tenacious D in The Pick of Destiny (2006). I know it's done in many films.
Anyway, you seem to concur that JB does break the fourth wall in that scene. I'm always interested in why it can be done in some films, and only in certain situations, by certain characters. It also interests me how the director, or writer, or actor knows that it can be done in a certain movie situation.