The finale of Peacemaker Season 2 has garnered mixed reactions, despite the overall strong reception of the season. A significant reveal in the finale involved the introduction of Salvation, a parallel dimension discovered by A.R.G.U.S. within the Quantum Unfolding Chamber (QUC), which now serves as a metahuman prison. The QUC, initially appearing in Season 1 as a mere pocket dimension for Auggie Smith's gear, evolved into a central plot device in Season 2, unveiling itself as a vast nexus of countless dimensions accessible through myriad doors. Each door promises a unique parallel world, and A.R.G.U.S. has gone from estimating hundreds to thousands of these dimensional gateways.

A major surprise that was nearly integrated into the finale, as revealed by series creator and DCU boss James Gunn, was a cameo by Marvel's fourth-wall-shattering mercenary, Deadpool, portrayed by Ryan Reynolds. Gunn disclosed in a press conference that during a sequence where the A.R.G.U.S. team explores the QUC, they were originally intended to open one of these doors and discover Deadpool within a room. The very concept of Deadpool appearing in the DCU through such a mechanism is inherently wild and would have marked the first major cinematic crossover between the multi-billion dollar franchises of Marvel and DC.

Deadpool's character is renowned for his metatextual humor, frequently breaking the fourth wall to address audiences or reference external franchises. A cameo in Peacemaker would necessitate breaking multiple fourth walls, signifying an unprecedented cinematic event. James Gunn took concrete steps to explore this possibility, engaging in discussions with Ryan Reynolds, who reportedly was keen on the idea. However, the logistical "pretty, pretty big hoops" required to facilitate such a crossover ultimately proved it "didn't feel doable" at the time.

Gunn has previously expressed openness to Marvel-DC crossovers, mentioning discussions about it "a billion times" and that it "could easily happen," but emphasized the need for it to "come from a real place" and be genuinely meaningful. Ultimately, the decision was made against the Deadpool cameo, primarily to prevent it from overshadowing the crucial events of the Peacemaker finale. Gunn candidly remarked that "That’s all anybody’s going to talk about now is f***ing Deadpool in the other room," acknowledging that fans and media would inevitably prioritize a Marvel-DC crossover over the narrative of the series itself. While the cameo would have been a humorous interjection, it would have lacked interaction and genuine plot relevance, potentially leading to endless, baseless theories without adding substance. Both Peacemaker and Deadpool share thematic similarities as foul-mouthed anti-heroes who find a chosen family, making an interaction between them priceless. However, for a major Marvel-DC crossover, it was decided that such an event should be more substantial, benefit both studios in significant ways, and ideally unfold on the big screen, reserving the possibility for a future, more impactful occasion rather than a mere non-interactive joke in a spin-off series.