In my unreleased Apocalypse World superhero hack, each playbook includes a move that allows the PC to have some degree of retroactive narrative control. Retconning happens all the time in comics, and as my hack's goal is genre simulation, retconning needed to be baked-in.
For example, The Detective playbook has the following move:
Strategic: When you want to retroactively make a plan now, explain when and how and roll +Clever. On a hit−, you didn't. On a special+, you did and hold A. If improved, or hold AA. Hold A: While you have 2 or fewer holds from this move, you may spend 1 hold to • have another take +1 forward • have something useful • let someone enter the area • let someone exit the area • reposition someone • take +1 forward.
When made successfully, the move effectively lets Otterman stop everything and explain to the other PCs that, while on the Otterplane on the way to Dr. Mastication's lair, they talked about this exact situation. A brief role-playing interlude occurs as Otterman explains the plan, and the mechanical benefits are realized.
And, for example, The Savage playbook has the following move:
Destructive: When you want to retroactively destroy something now, explain when and how and roll +Tough. On a miss, you didn't. On a hit, you did and pick AA. On a special+, you did and pick A. If improved, take +1 forward. List A: It • can still be salvaged with time • caused some collateral damage when you destroyed it • hurt you when you destroyed it.
When made successfully, the move allows Grenadedroid, as Dr. Mastication is about to escape in his Soviet-era diesel submarine, to explain that while the other PCs were exploring Dr. Mastication's lair, Grenadedroid found the diesel fuel storage. Never one to waste an opportunity to be destructive, he blew it up. In the process, Grenadedroid was slightly injured, as that's what happens when one mixes grenades and diesel fuel. Cut to Dr. Mastication swearing at our heroes from his unfueled sub and a previously unrevealed sliver of fuel barrel protruding from Grenadedroid's back.
(Both of these examples are pulled from my hack, so the language differs from that of stock Apocalypse World, but what effects the moves have should be obvious to those familiar with the game's engine or other hacks (q.v. Dungeon World, Monster of the Week).)
The playtesters—my regular and very conservative and traditional gaming group that I enlisted to help me with the Sisyphean task of playtesting a superhero game—were as wary of taking such narrative control away from me as I was about giving it to them, but over the course of several sessions such moves ended up receiving no greater or lesser attention than any other moves.
Hacking this into Leverage
The main Leverage characters by season 3 are superheroes, almost to the point of parody. For example, once it became clear in the series that Eliot never loses a fight unless he decides to a lose a fight, determining why he chooses losing becomes more interesting than the fight itself. That why is often the retcon point—a short-term failure later aiding in a long-term success.
Unlike a superhero game, a Leverage-based Apocalypse World game would require constant retconning. I'd consider replacing a character's sex move with some kind of move usable when a character is either detected (for the grifter, hacker, or thief), defeated (for the hitter), or outwitted (for the leader) that lets the character turn being detected, defeated, or outwitted into a later success. However, I haven't tried this.
To Sum Up
Such narrative sleight of hand like the kind you want is more easily accomplished in a system that relies deeply on the master of ceremonies to determine the outcomes of PCs' actions. Running Leverage using a more nuts-and-bolts system (cf. Spycraft 2.0, which handles admirably all of the show's characters' abilities) typically means sacrificing the retconning that makes the show's plots so engaging.