FAQAdd to FAQ (Coming Soon)
It's possible, as a sign of utter contempt, Wade refuses to refer to Ajax by his chosen name. It also adds more humour to the interrogation montage due to Wade getting increasingly frustrated at the fact that he's not getting answers out of anyone while he's asking them "Where's Francis?". It's also possible that Wade, not being the most stable individual, knew that the henchman probably wouldn't know Ajax by his given name and considered their ignorance as a lack of co-operation, giving him an excuse to kill them all. Edit (Coming Soon)
In an interview, Stan Lee revealed that he filmed his cameo in a studio, and was edited into the strip club scene. However, he joked that he was "Damn mad about that..." not because he was edited into a strip club scene but because he wasn't actually at the strip club. He joked that he'll insist on being on location for his strip club cameo in the sequel. Edit (Coming Soon)
During closing credits there are cartoon-style animations. There are scenes after the credits. The actual credits themselves that are immediately after the movie, as they were at the start, are part of the post-movie scene but the animations during the opening credits are not cartoon-style. Once ALL of the credits are over, there is a scene at the very end (actually two, second one comes after a short blackout). Read more about it here. For a more detailed description of all extras during and after the credits, go here. Edit (Coming Soon)
Daniel Cudmore, who played Colossus in 3 of the previous X-Men films said he was asked to reprise the role. But he would be CGI the entire time and also they wanted to use another actor's voice. So, Cudmore graciously passed on the opportunity. Colossus was recast for this film and is more accurate to his comic-book counter-part. Reasoning isn't given in the film, but Deadpool does make a joke to Colossus about how confusing the timelines within the X-Men franchise are, with different actors playing the same characters., perhaps as a nod to the recasting of Colossus. Edit (Coming Soon)
It has been speculated that Wade belongs to neither the "Stewart" nor the "McAvoy" timeline, since he exhibits awareness of Charles Xavier bearing either of the actors' likenesses, placing Wade in a sort of X-Men metaverse. More likely, the references are part of many times that he breaks the fourth wall—even the "sixteenth wall". This bit of information coupled with the fact that he is forgetful (at least regarding his bag full of ammo) and nothing about his background is revealed in Deadpool opens the door for a world of possibilities, particularly concerning the effect of his mutation on his brain, but it at least seems unlikely that this incarnation of Wade ever experienced being transformed into Weapon XI (Weapon 11, the 11th Weapon), who was decapitated at the end of X-Men Origins: Wolverine (2009) (2009).
Some possibilities (which may not be mutually exclusive) are as follows.
(1) Somehow or for whatever causation mechanics, in the Deadpool timeline, Wade's parents conceived him (exactly him) in the 1970s, instead of the 1940s like the original timeline. (This is not necessarily unusual in science fiction, since there are a number of stories in which a character travels to a world that experienced an alternate history different from ours by virtue of an event that happened before the same character or a younger character was born, thus ignoring the butterfly effect.)
(2) In any timeline or every timeline, Wade was indeed born in the 1940s or much earlier, but ages very slowly (much like Wolverine) or had served as something of a "winter soldier" (an operative who is placed into cryostasis whenever not on active duty)—skipping forward through time by the implied means or some other means.
(3) Wade is actually "Wade, Jr." or "Wade 2.0", whereas the man who became Weapon XI in the original timeline (or even the Deadpool timeline for that matter) was his biological father who looked just like him or even an individual from whom he was cloned.
(4) X-Men Origins: Wolverine has been retconned once again (for the second or third time, the 2½th time) and in such a way as its events never occurred in any canon timeline, or an "oversight" took place (again).
(5) Deadpool as a whole is merely a tongue-in-cheek fest that happens to have very dark thematic elements, not to be seriously treated as as part of or adjunct with the X-Men movie continuity. Edit (Coming Soon)
While the breaks of the fourth wall (of which many references are apart) in Deadpool may not be meant to be taken as anything other than a sort of a comedic Chorus, it would seem that Wade only begins making out-universe/world-beyond references (which are not even necessarily through the fourth wall) after having undergone the procedure to rid him of cancer, whereupon he started developing memory problems. As such, in addition to his brain being messed up and his mind disheveled, he may have developed some kind of low-level interdimensional perception. The star, Ryan Reynolds, is not exactly a stranger to this, as he played an interdimensional being before, in The Nines (2007) (2007). It's possible that the script for Deadpool was hinting at it with Wade's "sixteen walls" (four walls compounded) remark. However, by virtue of the opening credits and title cards, the movie itself is self-referencing, which obfuscates the nature of Wade the protagonist. Also, the interdimensionality is not a previously established ability of Wade's own, such as in the comic book lines on which the movie is based. Lastly, there is the matter of the Weapon XI action figure, but for all the audience knows, if the toy physically exists in Wade's world, Wade dreamed of Weapon XI itself (in a nightmare, of course) and molded a miniature of it himself. Edit (Coming Soon)