It's showing the extensions of UNKNOWN file types. But it looks like it's suppressing the display of KNOWN file types (there's also what looks like a PDF with the extension not showing - file type column says "Adobe Acrobat Document"). I'm a Mac guy but I vaguely recall that Windows has a way to control whether or not KNOWN file type extensions are shown as well as a way to define known file types.
Edit: When I say known filetype, that means it's in a table Windows maintains of file extensions and the program that creates that file type.
