The Dreamcast one was unfortunate, what with the magazine Action Replay disc giveaway being what opened up the console to mass piracy.
But the others were just hilarious. Like giving away a demo disc with the full game, then leaving a level select code on it so people could skip past the end of demo notice. Or sticking your new big name game on the back of a budget game's tape. Can you imagine if that happened now? Like, Pokemon Sun was included for free on Kirby Planet Robobot cards by mistake? It'd be one hell of a trainwreck for Nintendo.
So yeah, pretty amusing huh?