After Jack's outburst, Kate is holding him on the couch. As the shots shift from them to other characters and back, Kate is sometimes stretching the neckline of Jack's sweater and sometimes not.
When Jack has an accident skiing and falls down, snow is covering his sweater and pants. A few minutes later when he is being lifted into the doctor's office, there is no snow or any moisture anywhere on his clothing.
At the beginning of "Autumn", leaves are falling as a blue Mercedes sedan whooshes by (The camera catches the right side of the car.) on a curvy road. All that is seen is the right side/front of a late '70s/early '80s S-class Mercedes (likely a 450 SEL or a turbodiesel variant of the same body style). However, in the next shot, the car shown is the same color, but clearly is a 300 class (300 Diesel or 300 Turbodiesel). The latter is used in all interior and exterior shots throughout the Autumn (at the Connecticut inn) and eventually sinks on thin ice in "Winter".
When everyone drives out onto the frozen lake in the Mercedes to rescue Danny, all four windows are rolled up. However, when the car begins to sink, the front passenger side window is suddenly halfway down.
As Jack (Alan Alda) prepares for his big ski jump, he throws off his coat while standing in a wide field of snow, but when he starts to move in a far shot, the jacket is nowhere to be seen.
The boat scene when it hits the sandbar a crewman is visible.
In the final scene when the Mercedes sinks through the ice, two rigging lines are visible running across the ice on to shore. A crew person hidden behind a tree is briefly visible at the end of the shot.