Deliberate mistake: Coming back to Earth in 1998, Stone is amazed to see the Cincinnati Reds and the NY Yankees on TV in an interleague game. This wasn't yet possible in '98, as an American League East team could then play only a National League East team (and the Reds are NL Central). But the producers put it in anyway as their own little "fantasy baseball game," because these were their favorite teams.
Deliberate mistake: Garrity blackmails the town citizens into paying him not to resurrect their unlamented "loved ones." Amazingly, every man in the saloon just happens to have hundreds of dollars ($500 - $1200 each) in his pocket to pay up with. In 1890 money, that's roughly equivalent to a group of modern-day bar patrons all carrying ten to thirty thousand dollars around in their pockets. The scenario was apparently used in spite of its incredibility just to more quickly advance the plot.
Deliberate mistake: Right before rising to check out who was calling her name, Hannah sets her laptop, which she was using to write a letter, on the bedspread. The computer screen is shown to be blank, meaning, 1. she switched it off, which she didn't, or 2. it was out of order, which doesn't make sense since she was using it seconds before. (00:02:10)
Deliberate mistake: In Episode 7, "Bad Moon Rising": When Cash meets Sasha at The Haven, she mentions "Eddie and his bodyguards being blown away". But Eddie was not "blown away", he was neatly decapitated, and in addition, none of his bodyguards were killed. Julian specifically said that he would let them live to elect a new leader. Sasha was present, and would know this.
Deliberate mistake: At the end, a line apparently cut earlier creates slight confusion. Nick says to Nat, "When LaCroix asked you why?" (why save vampires). In the earlier scene as shown, the elusive LaCroix spoke only briefly to Nat in the lab, and never asked her that question. (00:42:20)
Deliberate mistake: Stranger Things season 4 vol 1 confirms upside down is locked in 1983 as Nancy's guns aren't there. Her diary entry shows it to be Nov 1983. Yet in season 4 vol 2 Ed Munson's guitar is there. This implies he either was playing guitar back then or they've made a deliberate mistake here but it's caused an error in the 'stuck in 1983' story.
Deliberate mistake: Inside the home that has been infested with Evil, the state police confront a possessed girl who attacks them. After some futile gunfire, the possessed girl is still standing. The female officer goes for her backup gun, which for some reason is a small over-and-under Derringer (meaning she has two shots maximum). She ends up firing the Derringer five times in just a few seconds, with explosive damage and without reloading. Director Sam Raimi probably staged the 5 gunshots on purpose, knowing that a two-round Derringer was a ridiculously-limited piece of firepower. Raimi probably did this as a tongue-in-cheek tribute to Ash's bottomless double-barrelled shotgun from Evil Dead 2 and Army of Darkness.
Deliberate mistake: Rick is talking to Joe in a maximum security facility through glass without a phone. It is impossible to hear through such glass. One would literally have to scream and still it would be difficult to hear. They should be on a two-way phone and those conversations are at times recorded, especially with high profile prisoners like murderers, mafiosi, terrorists. There's no way they would get away about discussing murder and revenge without an intercept. (00:14:00 - 00:15:00)
Deliberate mistake: The Korean lady's Mini-Uzi never runs out of ammunition, and she's spraying it at full-auto. A Min-Uzi's cyclic rate is 950 rounds/min. One long squeeze of the trigger and the weapon's dry. Same goes for all the other weapons like the M4 carbines being fired on full-auto, they have the infinity ammo cheat code going here.
Deliberate mistake: The police force in the town is the Gendarmerie, the standard issued firearm is the Sig Sauer P2022 in 9mm. The police officers on this show carry a Beretta and not the 9x19mm one which is the model 92fs, they carry a never issued Beretta 84 chambered in .32 acp or 9mm short. Plus they use some weird holster where the gun arches out and hangs low like a cowboy holster and dangles around. Easy for a suspect to gain control of the officers gun and this happened in this episode.
Deliberate mistake: Though by 1964 it was already suspected (and later confirmed by Mariner IV) that Mars has an atmosphere humans can't breathe and temperatures too low for humans to tolerate, Merritt and his crew are here exploring the planet sans spacesuits. This was "fudged" because space helmets A)are expensive, B)reflect cameras, and most importantly, C)obscure the actors' faces. (00:24:00)