At 24:06, Ritchie and his girl sit down on the large rock in front of the porch and it slides backwards.
Richie, Potsie and Ralph head to a cabin in the Wisconsin woods for Easter break. The cabin owner Tom as well as the 3 ladies staying at the cabin are attired for summer weather in the evening. It is much more likely to be cold and snowing at that time of year than short/tee shirt weather.