This is how my iTunes extras appear for the film Thor which I think is the way they are meant to be displayed in iTunes 11 (Notice there is a button under the year to play the extras)
If you right click on the movie and click 'Show in Finder' the iTunes extra file should be a .ite
Then again it could be that for Pulp Fiction the extras are just a .m4v file which could imply why they are showing as a separate movie.
If you delete the items in iTunes but keep the files. Then access iTunes folder in finder, make sure both film and extra are in the same folder. Drag & drap to desktop and then drag and drop (from desktop) to the film category in iTunes
Ta da