There are some phony "widescreen" films out there that apparently do nothing more than add the black bars to a fullscreen format. A Christmas Story supposedly does this...
I don't really see it as phoney. As I mentioned, I have sometimes seen microphones in their entirety in the area that is blacked out in the final version. I saw as story on this over a decade ago. Even though the film was shot in "tv" aspect ratio, the artistic vision was in the taped off "widescreen" area, which is why the director would sometimes miss things in the top and bottom areas like mics - and con-trails in westerns.
That said, I noticed it in My Bodyguard because the tops of peoples heads were cut off in the letterboxed version. It looks like it was filmed for tv aspect ratio.
Many 35mm cameras shoot an academy-ratio (1.37:1) frame. Some mask off the top and bottom; others simply leave it in and expect it will get cropped either in projection or in video conversion, or else that it will simply not get cropped but hopefully won't contain anything too annoying.
I am actually somewhat puzzled by why it would be so common to use a camera that uses an academy-ratio area of film for each frame and masks off the top and bottom; it would seem that one could save 25% on film costs if one were to make camera and projection equipment that could be set to advance film by three sprockets per frame instead of four. It would seem a simple standard to define and to implement mechanically.
On a related note, does anyone know if a full-frame El Mariachi is available? Since that film was shot on 16mm for video use, letterboxing it cuts out picture that was supposed to be seen. In Rodriguez's "Ten Minute Film School" clip he shows some of his original edited video (he originally shot the film on 16mm, then copied it to video and edited that); the framing is much better than in the "real" movie version which is cropped on the top and bottom.