My best guess would be that there is a utf multibyte char between the '''s, and vim is displaying the glyph associated with the first byte ascii value 128+ and that emacs recognises that it has a utf char, but the installed font doesn't have a glyph for the value, so its displaying a ? instead.

Try opening the scriptfile with a hex editor (or piping it through a bin 2 hex filter and see what value you have between the ''s at that point in the code.

Short odds that it is actually 2 or 3 bytes rather than a single byte char.