Set after World War II, Finlay tells a long story to Leroy about how his grandfather was murdered 100 years previously in 1848. Finlay would have to be in his 60s or 70s for that to be true and he clearly is not; it must have been his great-grandfather that was murdered.
As Finlay breaks the window with his gun, large pieces of broken glass are still visibly hanging in the window frame. In every subsequent shot of Finlay at the window, there is no broken glass hanging from the window frame.
When Leroy reaches to pick up the address paper that Montgomery drops, the reverse angle looks up to show the room ceiling. The lighting reveals that it is obviously fabric stretched (badly) over a frame.