Continuity mistake: During Clark's rant, the shot goes from seeing him from behind the whole family to a frontal view of the family looking at him in shock. In the first, they are standing in line with the entrance to the room. You can even see Eddie's shadow on the wall as he's very close and slightly behind it. Also, on the other side, Audrey's arms are going down to her side and she's a little behind Art. In the next shot, there is no wall and Audrey is in front of Art. Her arms are also crossed.
Continuity mistake: When Clark is looking at his "bonus check", he's holding both the envelope and "check" together in both hands. In the next shot he's only holding the "check" in both hands and the envelope is no longer under it.
Continuity mistake: When Clark falls over while on the ladder, after ripping his sleeve off, his hands keep changing position on the ladder. When he first starts to fall, his right hand is gripping the side and in the next shot both hands are gripping the rung. In the next shot both hands are on the side of the ladder until the shot after he pushes himself away from the tree and they go back to being on the rung for a shot.
Continuity mistake: The entire Christmas bonus scene at end, Clark's tie changes. Take note of the pattern on the knot, which changes from shot to shot.
Continuity mistake: When Clark is talking to the pretty saleswoman and she says "well, you do have your coat on", he tilts his head down and to his right. In the next shot his head is to his left and he moves it to the right.
Answer: They didn't go to a Christmas tree farm. He took them to a huge forest to get one most likely because it would be easier to get one free then to pay for one.
They went to a tree farm. After running off the road and jumping the snowbank the wagon crashes through a sign that says "Trees." Clark then says, "We're here...and we made good time too." The humor is Clark forgoes a normal "farmed" tree for the "wild" monster he takes home.
False. They may have run over the tree farm sign, but they absolutely did not harvest a tree from the tree farm.