Peter's house has a pitched roof that comes to a point at the top.
However when Peter and his friends are all having fun in the attic you clearly see the sides of the roof come to an angle then there is a flat section along the roof line.
Clearly this does not match the outside angle of the roof.
There are dormer windows and regular windows shown on the outside of the attic on the house but when Peter and his friends are shown up in the attic there are no windows visible.
After Lois screws the attic stairway closed to keep Peter and his friends locked up there, they are complaining they can't get out of the attic.
However there are dormer windows shown on the outside of the attic of the house which they could easily use to escape.