Yeah I see what you mean, something is clearly wrong in the code somewhere. I've just tried it again on my Android device and it is displaying the mobile versions on all pages.
The attachment shows screenshot from my phone showing how it should look. It should have a 'hamburger' icon to reveal the drop down menu rather than displaying it like the desktop version. You could try clearing your browser cache to see if that helps. It looks like you are still getting the desktop version and it's being compressed and cut off due to the portrait orientation. See what happens when you turn your phone sideways so it's in landscape view.