A federal task force of the nature depicted in this series would not need to ask the warden's permission to place an undercover officer in his prison. Blythe could have arranged it through his federal contacts. That being said, getting the warden's approval would be the best practice.
When Luke's gun jams in the final fight, an experienced field agent would not shout "My gun is jammed." He would know how to remedy the malfunction quickly and continue the fight.