Revealing mistake: None of the candles were flickering, which indicates they were fake. (00:24:30)
Revealing mistake: When the five friends are eating "snow cones", snow is falling in different directions in the two windows: diagonally to the left in the window to the left and diagonally to the right in the window to the right. (00:15:55)
Revealing mistake: When River and Eden are talking in front of the kitchen window, every other camera shift alternates between different backgrounds - still/blurred versus clear/actively snowing. The props are also different. (00:14:15)