Deadpool might have blown away the box office for having the biggest opening day ever for an R-rated film, but it also blew away the competition for most movie mistakes in 2016. According to the Movie Mistakes website, Deadpool featured 23 mistakes, with 19 of them focused on some kind of continuity error.
It wasn't a close call by any means, Zootopia followed with 13 mistakes, Captain America: Civil War tied for the second position and Now You See Me 2 took third with 12 errors.
A majority of Deadpool's mistakes had to do with continuity, for example:
"When Vanessa and Wade are having sex, her tattoo moves to her right breast on Halloween, but is on her left every other time."
Other mistakes in the film were dispersed between factual errors and visible crew/equipment – you can see the breakdown here. Whether or not the film had an abundance of errors doesn't really matter, it's still well on its way to a sequel – though they have to figure out who will be the director.