In Backrooms (2026), during Clark's first visit, the slippers and shoes he finds fused into the floor are the exact ones Bobby and Kat were wearing while they were filming that Captain Clark commercial back in the real world - meaning the complex was already copying their belongings even before they themselves ever entered the Backrooms.
The shoes being permanently swallowed by the floorboards act as an eerie foreshadowing: the Backrooms doesn't just copy objects, it copies the people and moments associated with them based on intense human memory. It implies that by being so deeply embedded in Clark's memory and his proximity to the Null Zone, Bobby and Kat's identities had already been marked and absorbed by the complex long before they ever set foot inside