"Merc with a Mouth" that is the famous Deadpool's nickname. The anti-hero that super talkative. Sure, all his jokes in the movie are funny. But, there is something important (that could make the movie even funnier) that missing. It is:
Deadpool's other personalities or Deadpool's inner voices.
In the comic Deadpool usually have these white boxes and yellow boxes to indicate the voices. While these white boxes express Deadpool's monologue like in other comic books character, but since Deadpool is known as fourth-wall breaker, the inner voices can be "heard" by the reader. Also the white boxes filled with more serious personality and yellow boxes are plain funny and insanity.
Deadpool also talks and debates with his inner voices/other personalities.
The origin of the voices (in comic) is also hilarious! It all started when Deadpool hired to kill Daredevil. When suddenly Madcap come to meet him. Madcap himself has the power of insanity inducement beside his healing factor. Madcap tried to make Deadpool insane, but failed (Deadpool can't more insane,eh?). Madcap also failed to make Daredevil insane. The came Thor, Thor strike his hammer and the lightning turn Deadpool and Madcap into ashes. The ashes then regenerate to Deadpool and only Deapool. From then on, Madcap joins Deadpool in his head as his other voice. Madcap became the insane/creative voice (yellow boxes).
Surely, to make the voices origin exactly like in the comic would be hard or maybe impossible due to the broadcasting rights. But the studio can make it origin different way.
If the movie add this detail the movie surely will be more awesome!