Well I never

[maltrab]

The times I have watched Whoops and for the first time noticed the door to Compo's has moved, if you watch when Wally brings the mince pies he comes through a door to the right of the usual door

 

[Pearl]

Yes, I've noticed that. I think the revolving door of set designers had a lot to answer for.

 

[captain clutterbuck]

the mince pies

The answer lies here , its clearly an optical illusion , it's your old mince pies playing tricks on you guv'nor !