Is a sentence under section 654 of the Criminal Code that includes multiple punishment available to the Court of Appeal reviewable as an unauthorized sentence?

^4. The record shows that neither party objected to the trial court's failure to stay the sentence under count 5. However, the section 654 multiple punishment claim raised in this appeal is reviewable as an unauthorized sentence, a sentence that could not lawfully be imposed under any circumstance. (People v. Scott (1994) 9 Cal.4th 331, 354, fn. 7 ["it is well settled... that the court... imposes an 'unauthorized' sentence when it erroneously stays or fails to stay execution of a sentence under section 654"].)