Deliberate mistake: When Nico finds Hilda's body at the start of the movie, her left arm is shown next to her body, and her right arm is outstretched. When her death is shown later in the movie, both arms are outstretched when she lands on the floor. (00:05:50 - 01:30:55)
Deliberate mistake: When Phoebe is about to destroy the lion statue, police cars arrive at the scene. Barely a second and a half later, suddenly the place is filled with cops who have managed to park the cars, step out, take positions, and aim. It speeds up the action of the film, but it's very awkward.
Deliberate mistake: In the housing block that Dave's house is in, the house numbers do not match - because In one shot of Claire walking past Dave's house, you can see that the house numbers are in the 1500's - one homes number is clearly 1516. However Dave's house number is 1958. However this is a deliberate mistake as the 1958 on Dave's house is a reference to when the Chipmunk fever was born. (00:23:50 - 00:32:35)
Deliberate mistake: When the natives abduct Dwan, they grab her and leave in a nanosecond, leaving nothing on the deck. When Jack arrives, there's suddenly a necklace on the deck which helps him figure out what went on, despite being a ludicrous and deliberate McGuffin. Check the beer can and red box as a reference.
Deliberate mistake: In the Spanish release, the name of the family store is written in Spanish, but inside the place it's in English everywhere. This is a very common mistake in foreign kids' films released in Spain.
Deliberate mistake: Conan Stevens' character in this film is an unnamed orc who briefly attacks Gandalf and is defeated by Galadriel. However, in the first movie, the same character briefly appears in the flashback to Moria and is credited as "Bolg." This is due to the role of Bolg being recast and the two remaining filmed scenes of the original actor being repurposed. The filmmakers originally intended for first film Bolg to be a younger Bolg, but later retconned this, despite already crediting him as Bolg.
Deliberate mistake: During "Nobody Cares Like a Bear," Kim opens a gift box containing a balloon. Secret Bear then grabs it and floats away. But when Grumpy Bear tosses a star and pops the balloon, confetti flies out of it and, for the next second, keeps reappearing from nowhere. (00:14:05)
Deliberate mistake: Before Superman traps the black missile, its beam is really big and covers half of the lettering on the side. When Superman is behind, the fire is much smaller and the lettering is visible, allowing us to see Superman.
Deliberate mistake: Luke had a box of T-shirts he designed and Faith reached into the box and removed the top T-shirt. Without looking at the size or even holding it up to her body to see if the T - shirt would fit, Faith asked, "How much?" Luke replied, "Ten" [dollars]. Faith reached into her pocket, pulled out a wad of bills and handed it to Luke without counting the money. Faith put the T-shirt on over her top and it was a "perfect fit." (00:03:55 - 00:04:37)
Deliberate mistake: Gonzo and Rizzo are selling apples in the beginning, including the Red Delicious cultivar. That wasn't invented until the 1880s and the story is set sometime in the first half of the 1800s. Most likely intentional as they are the narrators.
Deliberate mistake: When a man bumps into pole, it sounds as if a truck had crashed (which makes it funnier), but in reality he just bumped his chest.
Deliberate mistake: Baron Munchausen sends his courier, Berthold, on a one-hour errand to procure a bottle of the finest Tokay from the imperial wine cellars in Vienna. Berthold returns with the bottle within the hour and (in one continuous wide shot) hands the bottle to Baron Munchausen, who then hands it to the Sultan, who effortlessly plucks the cork from the bottle with his fingertips and pours a glass for himself. But there is no way the Sultan could simply pluck out the cork with his fingertips in one move; this extremely valuable bottle of wine is visibly sealed (in every shot) with a thick, air-tight red wax. This wax must first be cut and peeled away to access the deeply-embedded cork, and the cork must then be removed with a wine key (corkscrew). The action of properly opening the bottle would have required more time than the entire scene itself; so, to expedite the flow of the shot, director Terry Gilliam deliberately chose to forego a proper uncorking.
Suggested correction: You're ignoring the fact that the entire scene is a story the real Munchausen is telling from memory. There are many fantastic elements that do not hold with reality, like him riding his horse out of the window, falling several stories, and landing safety, or Adolphus being able to see and shoot to the other side of the world. The bottle is simply an example of Munchausen not adhering to reality.
In any event, the Sultan's effortless uncorking of the bottle was a deliberate mistake intended to allow a whole series of actions to occur sequentially in the single wide shot in less than 5 seconds.
Yet, at the end, Sally addresses Baron Munchausen directly and asks him the question that the audience has been wondering throughout the whole movie: "It wasn't just a story, was it?" The Baron solemnly shakes his head, affirming that he was telling the truth all along, regardless of how fantastic it sounded. This point is often missed by the movie's critics.
The point I raised wasn't that the Baron's story wasn't true, but rather that he embellished it.
Deliberate mistake: When Violator turns back into Clown in the alley, watch closely. You can see his shadow beneath him for a few seconds as he's transforming, and it doesn't match the transformation of the giant monster into the Clown... it's just Clown's regular shadow from the actor standing on-set. More than likely, it's a shortcut for the effects - they didn't bother rendering a simulated shadow. You have to look kinda close to notice it the first time, but once you see it, it's obvious.
Deliberate mistake: Just after arriving in the 21st century, Thibault and André enter an elevator and scare away its occupants. Attempting to chase them, the elevator doors close despite their attempts to keep it open. Elevators have a safety mechanism which opens the door when they encounter resistance. This was ignored deliberately in the film for comic effect.
Deliberate mistake: The surviving passengers are all awoken from a deep sleep after Dinah realises the other passengers have gone. Yet none of them appear drowsy or tired and none of their eyes appear strained, despite having just woken up so suddenly. (00:09:20)
Deliberate mistake: When young Odette is sliding down the banister, and gets stuck spinning around the end of it, it would be impossible to spin like that without her legs hitting the rail that she just slid down.
Deliberate mistake: Elizabeth will not be able to save Mateo from falling backwards into the fire pit by grabbing his hand or pulling him back after his whole body is suspended over the edge. (01:13:47)
Deliberate mistake: When C-3PO, R2-D2 and the younglings are driving through the battle zone, Anakin Skywalker and General Grevious can be seen battling. Later, Darth Vader can be seen on Hoth. This would be impossible due to Anakin Skywalker being Darth Vader. (00:08:50 - 00:12:20)
Deliberate mistake: All Minor Hockey Leagues in North America require players to wear visors with their helmets.
Deliberate mistake: Near the end, after the case is dismissed, people are celebrating, and we see a reporter talking, with snow flying around him. Cut to another shot of people watching a television. The snow has disappeared from the reporter's shot. It's likely that, since the snow was added in post, the filmmakers forgot to include it in that one shot.