There's an invalid URI within the IMG starting with http:\\ instead of http://. A mistake a beginner designer who's used to Windows directories would make. Some browsers like IE helpfully 'fix' this mistake and accept it so the beginner designers have no idea they're writing broken code. Other browsers like Firefox interpret it as written and show it as broken.

Hmm, with Chrome in W8 it shows an image, So I didn't see anything wrong...

The wrong slash has been used in the URL. It's supposed to be a broken image.