Continuity mistake: The way Charlie's necktie is tied and hanging varies during his first party. Sometimes, it is a little loose around the neck but the knot is tight and askew. Other times, the tie looks like a typical neat one. Interestingly, the tie is mostly loose and crooked at the beginning, but quite neat and typical after he eats the laced brownies (but goes back to loose and tilted). (00:26:08 - 00:28:03)
Continuity mistake: There are numerous instances (plenty even within the first fifteen minutes) wherein a character's hair changes from messy or strands hanging down or out to fairly neatly combed - far too many to point out at a particular time in the movie without being tedious and redundant (plus, this isn't necessary to be valid). For example, Mr Anderson's hair changes within a few seconds. There was a wad of hair sticking out on his left side, then it was neatly combed on the left side but the right side was disheveled. Patrick's hair, which is almost always messy, still has noticeable variations (such as dangling strands on one side or in his part) within seconds and/or when the camera changes position. Charlie's hair, in particular his bangs, frequently has gaps that are no longer present the next time he is seen. Given the number of hair continuity errors, they are best documented as one repeated mistake. (00:07:04)
Continuity mistake: Towards the end when Charlie is giving a goodbye hug to Sam before she goes to college, the sun changes between shots.
Continuity mistake: When Sam is preparing the milk shake for Charlie, the ice cream scoopfuls inside the blender change shapes from shot to shot.
