In a few endings, once you finish the credits, a post-credits scene will play. Stefan would be seen on the same bus from the beginning, and plays a cassette called "BANDERSNATCH DEMO". The audio would just be some beeps and bleeps, but when translated using a ZX Spectrum Emulator, it gives you a QR code leading to the Tuckersoft website, found here: https://www.tuckersoft.net/ealing20541/