Wrong direction slashes cause player not to play in Linux

The following example page plays in all browsers under Windows but does not play in Linux:
http://lingopolo.com/thai/word/airplane

When you look at the source and search for mp3 you see what looks like the problem, that the URL for the media file is:
http:\/\/lingopolo.com\/sites\/default\/files\/airplane_0.mp3

Amazingly this works in Windows, but not it seems in Linux. Is this the problem? Shouldn't this read something like:
http://lingopolo.com/thai/word/airplane
or are the escape characters really needed?