Misidentification is an interesting theme to use for The Great Gatsby. Gatsby himself is a constructed persona. People identify him as Jay Gatsby, a wealthy urban professional. But originally, he is James Gatz, a naive man from a small town.
Gatsby has this idealized vision of Daisy and it is something that she can never live up to. In addition to that, when he meets her again, years after their original courtship, Gatsby's vision has not changed. But Daisy certainly has changed. She still has feelings for Gatsby (Gatz) but she has moved on, gotten married, and become accustomed to wealth. She is not perfect. But Gatsby continues to view her as such. He, therefore, makes it a practice of misidentifying her. He shapes the idea of her identity in his mind, just as he shaped his own identity from Gatz to Gatsby.
It is Shakespearean considering how much misidentification occurs in the novel, particularly with the events leading up to the car accident. Prior to the car accident, Tom, Nick, and Jordan stop at Wilson's garage. Myrtle sees them and thinks that Jordan is Tom's wife. Upon noticing this, Nick adds:
There is no confusion like the confusion of a simple mind, and as we drove away Tom was feeling the hot whips of panic. (Chapter 8)
They are in Gatsby's yellow car at this point. It is also at this time that George Wilson is aware that Myrtle's been having an affair. However, Nick notes that he does not yet suspect that it is Tom:
The relentless beating heat was beginning to confuse me and I had a bad moment there before I realized that so far his suspicions hadn’t alighted on Tom. (Chapter 8)
On the return trip, Tom, Nick, and Jordan switch to Tom's blue car. Gatsby and Daisy are now in the yellow car. So, when Myrtle sees the yellow car coming back, she thinks Tom is in it. This switching of the cars seems insignificant unless we consider it as analogous to how Gatsby, Myrtle, and Tom switch romantic partners. In other words, with all of the affairs going on, confusion occurs. After the car accident, Myrtle's husband thinks Gatsby is responsible and that he (not Tom) is the one who's been having an affair with his wife. All of the lying and deceitfulness results in real violence. First, Myrtle is killed, followed by Gatsby and George Wilson. The lying leads to confusion and misidentification.