Joy is in jail and behind a partition while arguing with Catalina over the visitor's phone. Earl interrupts and in doing so, repeats some of Joy's dialogue. However, Joy is isolated behind a partition and Earl isn't on the phone. He should have had no idea what she was saying.
When Joy is seen copying a $20 bill in the copy store, the $20 bill she is copying is the colored $20 bill issued in 2003. However, Earl states that Joy copied the 20$ bill in 1996.