1) That Finale
The MCU has a finale problem. For some reason, Marvel almost always concludes its movies with epic set-pieces designed to dwarf everything previously seen in the film. It’s rarely ever an organic development, and tramples over any subtlety the film might have had.
Deadpool is as guilty as any Marvel movie of falling into this trap of believing going big for the climax is the only way to go. Only with Deadpool it seems an even more egregious mistake.
In the Marvel movies a giant, explosive finale is at least more in keeping with the more bombastic overall approach. In Deadpool, ending with a generic, special effects-laden set-piece and turning the tone momentarily serious doesn’t feel natural, it feels tacked-on and studio mandated.
Deadpool‘s finale is really its most major glaring weakness, a self-consciously Big moment that doesn’t fit with the intimate comedy style of the rest of the movie.