In Real Life, if you take two clocks at random the chances that they show the exact same time are fairly low unless someone's taking care of keeping them in sync.
In fiction, however, every clock and/or watch shows the exact same time of day. Always. Sometimes even ones in different time zones. All miserable cheapo wrist watches and all cell phones and street clocks run in harmonious synchrony with the precision of an atomic clock. Sometimes used for dramatic effect by highlighting the improbable, often significant timing of an event, or the fact that two remote, seemingly unrelated events happened at the same time. Normally fueled by Conservation of Detail. Nothing to do with Mirror Routines or Fearful Symmetry.
- At one point in the Medabots anime, the villain doctors footage of a fight between Metabee and his Kilobot to make it look like Metabee was cheating. The footage of the fight was broadcast live, but due to the doctoring it was delayed a minute. His plot was uncovered when Arika points out to everyone watching that the timestamp on the footage was one minute behind the "actual" time.
- One arc of Detective Conan took place in a house with hundreds of clocks, all of which showed the exact same time - because the owner of the house kept a team of clock repairmen on call 24/7 to ensure that this was the case. One of her previous employees died because she made the man climb the outside of the clock tower to fix the clock there in the rain, causing him to fall. This is why she gets murdered.
- One episode of Detective School Q had a deliberate aversion. A television broadcast of people evacuating an enormous department store due to a bomb threat showed the time being fifteen minutes later than the clock on the wall in the room where people were watching the broadcast. The broadcast was actually coming from a set - since the detectives didn't have enough time to thoroughly search the department store before the bomb went off, they chose instead to trick the already captured bomber into saying where he hid it after he believed it had gone off.
- Averted for the sake of a joke in the Italian comic Cuori Grassi. The protagonist — an overweight teenager — tries to psych himself up for a diet, and tell his friends to take note of the time, because it'll go down in history.
Friend #1: My watch says it's five o'clock.Friend #2: Mine says four-thirty.Friend #3: Mine's stopped.Protagonist: This is not a good start.
- In the opening scene of the first Back to the Future film, Doc's house is full of hundreds of different alarm clocks that he has painstakingly synchronized to all go off exactly 20 minutes late. Every single one of them.
- Subverted in Animal House. As the Alphas prepare their showdown, each looks at his watch, which are synchronized — except for Bluto's, which shows some completely random time. Could be justified if (other than Bluto) they deliberately synched them ahead of time.
- Justified in Die Hard 2, where we see the bad guys carefully synchronize their watches before splitting up to put their Evil Plan into action.
- A plot point in Thief of Time; Clockmaker's Guild member Jeremy Clockson is able to keep every single clock in his shop synchronized almost perfectly, even ones that rely on animals or plants to operate. He's so obsessed with keeping perfect time that he beat another guild member (possibly to death) for deliberately keeping his pocket watch a few minutes fast. As it eventually turns out, his ability is due to his being one of the two son (yes, that is written correctly) of Time herself.
- The rest of the city of Ankh-Morpork averts this; the bells that ring every hour are never in sync. It takes a while for all of the bells to settle down.
- CSI: NY. The 333 killer will time certain events to happen exactly at 3:33, and he can rest assured that's precisely the time Mac's clock will be showing.
- On an episode of NCIS, the Cyber Vid Character gives the time of his victims' deaths and then broadcasts the murder over the internet. One example is particularly egregious. He lists the time of death as five minutes to midnight. Two clocks were shown when the victim died, and they both showed the precise time, despite the fact that the poison that killed him was administered hours ago. There's Willing Suspension of Disbelief and then there's this.
- While NCIS is usually VERY guilty of this kind of stuff, that one actually worked. Both clocks were at the Naval Yard (military base). So it is highly likely the clocks there were actually kept in sync with a standard, especially when the time was very relevant to an ongoing investigation. And, because the killer mostly left the clue for Gibbs, he would have operated according to that time. The perfect timing of the poison is a completely different trope, of course.
- In The Legend of Zelda: Majora's Mask, all of the clocks in the game are synced to the In-Universe Game Clock, and as such, all of them display the exact same time. This is, however, justified in-universe by the fact that the game is set in and around a place called Clock Town. If there's anything you'd expect them to have down to a science, it would be timekeeping.
- The increase in internet and cellular connected devices is leading to most of them always showing the same (correct) time, as many of them periodically connect to, and adjust their own clocks by, atomic clocks that provide time accurate to less than a second. GPS devices also connect with the GPS satellites which each have an atomic clock on board (which is necessary for their function).