Continuity mistake: At Betty's wedding where Dunbar has just joined Katherine et al. at their table, Nancy gets up and makes her way round the table to ask Katherine if she wants anything from the bar. We see her arrive between Katherine and Dunbar. However in the next shot, she isn't there. It isn't until a few seconds later that she seems to appear again. (00:37:20)
Continuity mistake: In the scene where Dunbar gives Katherine her Christmas gift, the brick path that Katherine is walking on is wet and covered by ice and snow. When we have a closeup of Dunbar catching up with Katherine, the path is dry and has no snow or ice on it. (01:11:25)
Continuity mistake: During an outdoor campus celebration, students dance around a May Pole, winding ribbons attached at the top around it. The ribbons are wrapped around the pole about five inches from the top. In the next shot, the ribbons are not yet wound around the pole as the girls circle it. (01:23:00)
Continuity mistake: When Julia Roberts is sitting on the couch with the male teacher, after he pours her a drink, they move the camera and show her and her drink is almost empty and then they show him and the drink is almost full. They then repeat going from her with an almost empty glass to him with her glass almost full.
Continuity mistake: When Kirsten Dunst is getting married, and the bride and groom are having their photos taken, they talk about reading a poem, and Dunst hands over a piece of paper with the poem written down on it to her husband. When he takes it, he carries on holding her hand, but in the next shot, when a photo is taken, both characters' hands are down by their sides.
Answer: The colour change every year and the number is the year they finish (Joan's hat says 54 and their last year is 1954 as Nancy says around new year.)