It's halfway through the first volume before a Number 4 Cartridge is used HALFWAY! And I've not seen a reference to "Der Happy Schtick" yet!
Wulf uses it's proper name halfway through The Schicklgruber Grab, which is the first story when everything really clicks. And interestingly it starts sowing the seeds for future strip continuity with the SD Dispatcher Harvey being named for the first time and the appearance of an SD called Stix. He's got two brothers as we'll see in v2.
Argh, you know what I mean. They just don't work in that fictional set-up for me. As I've said before, it makes as much sense to me in overall believability in the universe as if they turned up in Coronation St. Or if Flash Gordon turned up in an episode of Rumpole Of The Bailey. Does not compute.