That's actually normal for widescreen movies whose aspect ratio is 1.85:1, like Penn & Teller Get Killed
(wider 2.35:1 "scope" films are shot differently). Movies were historically shot in a 1.37 aspect ratio (about the same as that of a standard television) until the mid-1950s, when the introduction of television inspired studios to adopt the "widescreen" process as a gimmick to get people to watch movies in theaters instead of at home.
However, they didn't use special cameras or film stock to achieve the wider aspect ratio. Instead, they continued to capture a picture on the entirety of a standard 1.37 frame of film, but actually framed the shot for a smaller 1.85:1 area within that frame.
This practice continues today. The monitor that the director and cinematographer use to compose their shot typically has markings on it to indicate the 1.85:1 area that will be displayed in theaters, but there is extraneous picture information above and below that area that does find its way onto the film. When a movies is released in "full screen" on DVD or shown that way on television, the frame is usually just "opened up" to expose this additional area.
So the viewer will indeed see more
picture information with the full screen version than with the widescreen one, but the important point is that only with the widescreen version will he see the image as it was composed by the director and his cinematographer
Sometimes, "opening up" the frame can lead to revealing mistakes. A Fish Called Wanda
features one of the most famous examples of this, wherein a supposedly naked John Cleese is shown to actually be wearing pants, which are hidden below the bottom of the frame in the properly-framed widescreen version. You can see a comparison of the two versions at The Letterbox & Widescreen Advocacy Page
If you know a little bit about film history and the way films are shot, it's not surprising that the widescreen version of Penn & Teller Get Killed
shows less of the image than the full screen version. But that's the way it was meant to be seen, so I'm quite glad that that's the version which is apparently being included on the DVD.