Continuity mistake: When Deadpool falls into the dumpster he has no swords, he left them behind. When he climbs out, they are on his back. They disappear again as he walks down the stairs to his apartment.
Continuity mistake: When Vanessa takes off Wade's mask at the end of the movie, he has a picture of Hugh Jackman's face stapled to his. When Vanessa removes the picture, the staple on Wade's chin is affixed and horizontal. In the next shot, it's hanging down. The third time we see it, it's back to position 1.
Visible crew/equipment: After Colossus and Negasonic Teenage Warhead leave the manor to go find Deadpool, the scene cuts back to the bridge where several gunmen are shown exiting cars and begin approaching Deadpool. In one of the shots during this, a gunman is shown exiting the seat of a car, with the camera placed behind him. In the shot, the reflection of a camera, cameraman and boom mic are perfectly visible in the side wing mirror.
Continuity mistake: When Wade and Weasel decide on the name "Deadpool," Wade is wearing gloves, but in the close-up, his hand is bare (and un-scarred).