When Frank is sitting on the window ledge it is clearly a vertical opening sash window. After he falls out he looks back up to see Charlie looking down at him through a horizontal sliding window.
When Frank is sitting on the window sill there's a brick building 10-15 feet behind him. Yet once he falls from the window he's in an alley that is clearly 20-30 feet across.
The doors for the Welfare office have 'Office of Social Services' written incorrectly as the people walking into the room would see the lettering backwards.