When Johnny/Eddie tells Micki that Eddie jumped him, he calls the man "Andy".
When explaining the charm early on, Johnny says that the user has to kill the body they plan to swap with. But Johnny doesn't kill Eddie before swapping with him, and Eddie doesn't die until after they swap back.
Johnny says that he used the charm on Eddie. But as we see twice, using the amulet means placing it on a motionless person and it taking 10-30 seconds to make the transfer. The broken-legged Johnny had no chance to use the charm that way on the mobile Eddie.