Apologies if this has already been mentioned, struggling to keep up with the mailing list!
I'm just watching the first episode on Sky+ and about 13 minutes in there's a shot of a Japanese guy's computer screen. In the background there are approximately a dozen icons on the desktop which appear to be various BeOS R5 ones. They've all been re-coloured and are heavily outlined and drop-shadowed (presumably to make them more cartoony) but I recognised the CD-ROM drive and Critical Alert icons immediately.
