Continuity mistake: At the end of the movie, when Alice grabs Dave and starts kissing him on the bench, she doesn't have any shoes on. A second later, in the next shot, she has flip flops on. Then the shot changes again and she is once again barefoot, without any shoes on. (01:29:40)
Continuity mistake: When Mike draws the line in the sand, a woman walks up in close proximity behind Dave. In subsequent shots in the same scene, she is gone, although there was not nearly enough time for her to move out of view in any direction.
Other mistake: After the weird scene with the dude in a wig, there's one quick display of all the various pages that talked about the viral video. One of those pages is written in Italian, but it's obviously machine-translated and/or not supervised by anyone speaking the language, since it contains multiple mistakes (including also an edit flub with the picture of the brothers on top of an article about medusae). Even the name of the magazine is certainly pretty bad for an Italian one; "Daily du Jour", which is French, not Italian. (00:14:15)
Other mistake: Mike and Dave put the ad on Craigslist, and people begin to share it through social media. The first time we see someone share it through Facebook the date of the post is "March 19 at 12:38 AM." Moments later there's a zoom in and now the date is still the 19th, still at 12:38 AM, but the month changed to May. (00:12:30)