On the bus ride after the Battle of the Bands, the bus is first seen driving down a street which could only turn left or right, it does not continue straight. However, in the next scenes it is seen driving forward only, it doesn't turn a corner.
When Ramona offers Scott tea at her house, she decides to have a cup of Sleepy Time Tea. We can see the box is from Celestial Seasonings; this brand of tea is well known for excluding the string and tag from its bag design to reduce waste. But as Ramona picks up her cup of tea, we can see a string and tag.
Scott orders an item from Amazon.ca, and Ramona, an Amazon.ca employee, delivers it. Amazon.ca ships goods via regular mail or Canada Post's Xpresspost system. Ramona delivers the goods using a short-cut through Scott's subconscious, so some leeway must be allowed. If such a fast, cheap delivery system existed, Amazon would surely adopt it.
Scott tells the band that he has learned the bass line from Final Fantasy 2, then plays the battle scene from Final Fantasy 4. The game Final Fantasy II was released as Final Fantasy 4 in Japan but re-titled as Final Fantasy 2 in the United States and Canada.
In the fight scene between Roxie Richter and Ramona, when the camera is behind Ramona, her real hair can be clearly seen underneath her wig. This is not in fact Mary's real hair but the bottom layers of Ramona's hair which are dyed black. In the final desert dream sequence these black layers can be seen when Ramona reveals the computer chip on her neck Gideon uses to manipulate her.
When Scott leaps up and goes to attack Todd across the table, and Todd holds him back with waves of energy, the girl drummer from TCAD is first leaning against the wall, disappears from the frame, and then reappears when the scene shifts. This is most likely a reference to the graphic novel where this character is able to teleport at will. She may be said to have teleported out of this location and then back into it.
Scott orders a caramel machiatto at Second Cup. Starbucks sells caramel machiattos; Second Cup serves caramel corettos. However, this is probably a reference to the graphic novel stating Scott didn't realize until the age of 23 that all Second Cup entrances do not lead to the same interior. Scott probably didn't realize before this that all coffee shops do not have identical menus.
Near the end, when Scott sits on the swing with his sister, she calls him "little brother." Stacey is 18; Scott is 22. This is a semi-repeating joke from the original comic; Stacey is seen as the more mature, "older" sibling.
It seems as if Scott's front door has a different handle when Wallace says "weren't you meant to take your fake high school girlfriend to the library a half-hour ago?" If you look closely, it's the bathroom door, not the front door.