There is wrongly positive matching in the following piece of code. Piece of code prints "wrongly positive" when one could expect no match exception.
I found this bug in production code and wrote this small reproducing snapshort

Array("a", "b", "c") match {
case Array("a", "x", "c") => println("x"); 
case Array("a", "b", "x") => println("a"); 
case Array("a", "d", _*) => println("wrongly positive")
}

Result: wrongly positive

The interesting thing about this code that without the first case it works correctly.