Near the beginning of the episode, there is a shot from outer space showing the storm. The storm shown is rotating clockwise. That would be a high-pressure system and is associated with fair weather. A system that would produce a storm would rotate counter-clockwise around low pressure.
In the very first shot of the episode, a Virgin Blue 737 aircraft can be seen touching down at an airport, presumably one in New York. However Virgin Blue (now known as Virgin Australia) is based in Australia and has never operated any flights to the US, let alone New York. The shot also displays a date of March 1998 however Virgin Blue was only founded in 2000.
While Marshall and Robin are discussing whether he plans to pick Lily up at the airport, Marshall is supposed to be working on the top center of the radiator beneath the window with a Stillson wrench (aka pipe wrench). However, all the mechanical adjustments (supply valve, air/steam valve/union connection/etc) are all located on the extreme left and right ends of the radiator.
Robin is from Canada, and since it snows in Canada they should have snowplow trucks to clear the snow on the roads. Robin should have known what a snowplow truck would do to cars on the side of the road when it passes by them.