Rotten lair in different seasons

[BRBFBI]

I think the stairway is there to connect the real path to the fake path on the billboard when viewed head-on from a great distance. It's such a funny idea that Robbie's lair would be concealed with a billboard painted with a natural landscape. It's something I never stop to think about when I'm watching, but the concept makes me laugh.

[LazyPooky]

There are more differences when you compare both pictures. It could be because of the difference between the episode seasons, like they made little reconstructions or the use of different CGI software. I think the summer landscape is from season 1 and the winter landscape is from season 3. There is almost a 10 year gap between the first and second picture.

[chuft]

What is that little stairway for on the left? It almost looks like there should be a stage there and the billboard is really a background picture for a play.

The stairway is missing in the winter picture.

[LazyPooky]

I found a picture of the above ground lair in summer, at almost the same distance as the winter landscape which is a screenshot from an episode. Funny thing is that the cow has icicle on her nose. Such details.