Plot hole: Jay is thrown out of the hotel pool for throwing a young boy into the pool, and Will is thrown out for insulting the girl in a wheelchair. At this time, Simon was in the cafe, nowhere near the other boys and not involved in any of these. So why would he be thrown out, too? How would the employee who grabs him even know they were together?
Plot hole: Hobson passes away in the night, and no one notices until Arthur wakes the next morning, finds her unresponsive and cold, then screams for the nurse. Hobson was hooked up to monitors to warn the nurse (and Arthur) of this very thing, and that nurse would have been making regular checks on her during the night; it's what she's being paid to do. There is absolutely no way it could have played out this way, except in a film that needs sudden drama.
Plot hole: After January Jones has just told Liam Neeson she doesn't recognise him. Neeson is trying to persuade Herr Strauss and two cops that he really is Dr Martin Harris of Langmore University, and suggests they look for a photo of him online. However, the cop using the computer says that it could take him ages to find a photo of Dr Martin Harris, as "there are more than 40 000 in the USA." This is very true, but as Neeson has already told him not only his name but also his place of work (Langmore university) in reality the cop would have found the photo far more quickly.
Suggested correction: The average cop wouldn't be that quick to realise that he could filter the results. Instead of being a plot hole, this is simply a very human initial response to an initial search result.
Plot hole: Smiley is at a hotel asking Sam what happened when he was duty officer on the night Jim Prideaux was shot. What Sam recalls (among other things) is he and Bill Haydon going through Jim's things. Haydon finds a photo of himself and Prideaux and sneaks it away in his pocket unseen by Sam. How could Sam explain that to Smiley when he did not see Haydon's move?
Plot hole: The very last scene shows Mary building a wall, apparently in her belfry. But there should still be the original wall that Rose built, with the hole in it that Mary smashed in. By killing Rose / having killed Rose, she prevents further harm, but all effects that took place before that (also the building of the wall), should stay (like her scars). It is very unlikely Mary broke down the whole wall just to add another body. (01:28:25)
Plot hole: They let the bad guy go because "lack of evidence", that should not be the case. We know from earlier we have the killer's voice on tape talking to the reporter, admitting everything. (00:40:00 - 01:10:00)
Plot hole: Ed discovers Jerry is invisible to video recording. However, later in the movie, Jerry appears on the surveillance camera when he attacks a hapless security guard at Peter Vincent's building.
Plot hole: How did the wolves get across the canyon? Unless they were flying wolves, there's no way they could.
Suggested correction: Just because we don't see how they got across doesn't make it a plot hole. We see next to nothing of the area surrounding the canyon. There could have been a pass or trail in the distance that the wolves used. The characters think they are gradually walking away from where the wolves' den is, so they decide to use a makeshift zipline to get to the other side rather than go back the way they came and risk running into the wolves again.
Plot hole: Gail and Katie talk in her shed about Guy's phone call. Katie says "I didn't lie about anything", which is a really odd non sequitur. All Gail said was "I just got off the phone with Guy Morgan. Your phone. He just loved that little demo you left him. I have underestimated you. It'd make me proud if I actually cared about you." Nothing about it prompts a response like that, except the plot point that Gail told Guy that Katie lied about it appropriating Bev's demo. But Katie does not know that fact at that point. (00:21:00)
Plot hole: When the hikers heard the voice calling out for help, they were yelling "can anybody hear me" and "is anybody there" in English. Once they rescued her and they tried to talk to her, they said she didn't know any English.
Plot hole: When Sam first encounters Dan, the headmaster, Dan reveals that he had to quit his musical career when he impregnated and married a groupie, but that he loved his daughter. Later, Sam runs into Courtney behind a liquor store, and Courtney, who is actually Dan's above-mentioned daughter, discusses her "aggro older brother". If Dan's original error in timing resulted in a daughter, how could she have an older brother?