I noticed this bug twise on my first playthrough.
I had second playthrough where i tried everything i could to replicate it in various ways at various times to no success srry
meaning this is the best expaination and possible solution i can have
both times i came across the bug had to do with the car.
I used mouse and keyboard
how it looks: sam and max are standing by the car while yet you are outside the car and the (back x) is still on screen.
you can not click the (back x) or the car.
yet you can move around like an ivisible ghost while sam and max are still by the car.
Frst time i thought it had hanged on me because i could'nt use the (back x) to leave the car or click on anything.
second time i tried i could move using arrow keys and by entering stinkys returend everything was back to normal
so if anyone notices this. Don't panic just enter stinkys (and maybe other areas as well) to return everything back to normal.
srry i can't expain it better.:(
Was to impatient finishing the episode when i resolved my problem and forgot about the screenshot. (With such good games, who can you blame me;))
As said i have tried replicate it to during the last days with no luck, srry