Continuity mistake: When the earthquake begins, the floorboards start to break in two, and Alan starts falling so Sarah holds onto him. Watch the small circular window in the wideshot. (the window that the mosquito flew out of earlier in the film) To the left of the circular window are some empty wooden beams, but no items. When it then cuts to a closeup of the window breaking in two, items have appeared on the beams, and there's a banjo hanging up etc.
Picture added by Hamster