Not quite as fun but my mum works for postal services in Austria and there's a special stamp for mail accidentally sent to Austria instead of Australia
The volume of missent mail has certainly gone down in recent years due to both communication moving online and international post adopting more precise adress systems, but 10-15 years ago you could get parcels with multiple "missent to Austria - missent to Australia" stamps on them due to some incompetent people not realizing where it should actually go.
I went to Vienna for a conference for work in 2016. When I got back, I turned in my receipts, and the admin assistant helpfully typed up my reimbursement paperwork, carefully converting to USD from Australian dollars.
It was at that moment that I was glad I'd made my own flight and hotel reservations.