No filter in the gearbox. Just a magnet in the drain plug to check for any metal chunks/flakes etc. Gearbox needs to be filled via the dipstick tube (under intercooler) so have a funnel handy.
It makes sense to do the rear diff oil at the same time as gearbox. Some scoobs use the same oil for both (my bugeye does) but I've got a feeling thats not the case for all models so worth checking.