When Randy stares at the Wall Mart from his bedroom, Sharon Marsh is seen with and without her blindfold when she is in the bed.
When they see Marvin Marsh as a Wall-Mart greeter, Sheila Broflovski asks Sharon is that's her father, to which Sharon says yes. Marvin, however, is Sharon's father-in-law, and Randy's biological father. Sharon may have answered yes as Marvin is her Step - Father.
After Stan and Kyle destroy Wall-Mart's heart, Kyle says, "We have to get out of here!" but says it in Stan's voice.
When Randy Marsh goes to the Wall-Mart at night, to the left of the old lady someone further behind somehow walks closer. A man in the back was walking to the left, while a woman closer to the door was walking to the right; when the two crossed, the man was over the woman, with only her legs being shown.
When the boys walk up to the rebuilt Wall-mart, the 'W' in wall-mart is lowered twice between the scenes where they're walking in and walking out.
As the townsfolk sing "Kum Ba Yah", they are shown swaying and holding hands. However, in the next shot facing the Wall-Mart they are standing still and not holding hands.