Corrected entry: When Shane is pulling up to his father's house on Christmas Day, the radio is airing a report about the stock market taking a downturn that day. If it's Christmas Day, the stock market would be closed.
When Shane first gets into Studio 54, he is told to take his shirt off. He pulls it over the top of his head. Then he walks in holding it and even though he never unbuttons it, it is somehow unbuttoned when he puts it on again.