The Four Horsemen's logo, given to them in the apartment in the beginning? Foreshadowing AND Fridge Brilliance, in that it not only is a stylized 4H, but it is 5 rectangles connected together. There are five people in the Four Horsemen.
The Four Horsemen's first show has them activate the teleporter with Etienne in it, and then the scene cuts to "Paris - at the same moment". This only works in a visual medium: that two-second scene of Paris happens at the same moment Etienne gets teleported. The caption just fails to mention that the scene then cuts back to Las Vegas, to keep the misdirection.
Why are the onlookers applauding when the Four Horsemen are clearly being arrested by what is obviously the FBI? Because they've realized that the Horsemen didn't just rain money on the audience in Las Vegas, they actually took money from a Parisian Bank, and that is just too awesome to not applaud.
The Tarot Motifs that the Horsemen received are references to their fates, personalities, and ties to the plot:
Jack Wilder: The Death is a card of change, NOT about physical death. This signifies his change in maturity, not that he actually dies in a car accident.
J. Daniel Atlas: The Lover is a card about partnership (including romantic) and duality. He has romantic issues with his ex-assistant Henley (which are resolved in the end), while the duality part symbolizes his Jerk with a Heart of Gold personality. There is also his catchphrase (which is the movie's theme): "The closer you think you are, the less you'll actually see".
Henley Reeves: The High Priestess is a card of femininity, common sense, and intuition. She's the only girl in the Four Horsemen, and the movie uses a lot of Batman Gambits, which hinge on the mark following their intuition and common sense.
Merritt McKinney: The Hermit is a card of spirituality, including emotion, doing the right thing, and searching for the truth. He is a mentalist, and his Establishing Character Moment includes Merritt stopping a man from cheating again (though Merritt still extorts him). As for the movie, it is actually about a Roaring Rampage of Revenge to punish Asshole Victims.
Dylan Rhodes: He is called The Fool, and he moves the plot forward to avenge his father's death, whose Tarot Motifs is the King of Spades.
The Fool indicate newness and inexperience. Dylan is actually Obfuscating Stupidity and has been preparing the whole plan for years. It also indicates unlimited potential, and in readings is said to indicate the need for a leap of faith by those who draw it in a reading- which is a recurring theme throughout the movie.
The King of Swords indicates a strong-headed man prone to do things which affect him personally, but who disregards others. Dylan concocted a massive plan to enact his Roaring Rampage of Revenge because It's Personal, and placed a lot of people in danger for it to work.
Also, the possible first card is the King of Spades/Swords, followed by the Lovers, the Hermit, The High Priestess, and finally Death. Performing an actual five card reading with the King of Swords/Spades, the Lovers, the Hermit, the High Priestess, and Death in that order will pretty much sum up the course of the movie.
There are many indications that Dylan Rhodes knew a lot about the heists, beyond appearing as the hooded presence at the beginning of the movie.
For the first heist, he had no interest in the case until the Interpol agent shows up, which leads to him showing extreme interest in the magicians to possibly keep an eye on her.
During the second heist, Dylan shouts out the keyword, even though he was a member of the audience and knew the reaction the hypnotized audience members would have had to that particular word.
There is also his Keystone Kop routine when Atlas places his own tracker on Dylan. Ten calm seconds would have told Dylan that the tracker was on his person, yet he spends a good few minutes running around with his re-enforcements behind him trying to catch himself.
A clever clue involving Dylan's shouting of the keyword: Merritt tells the hypnotized members of the audience to tackle the quarterback. Dylan was the "quarterback" the entire time.
If anyone else had seen the body during Jack's escape attempt, they probably would have figured out it wasn't him. Dylan ran interference to make sure no one else could get a good look at the driver.
There is a huge hint during the chase scene: after Dylan and Jack drop into the basement down the garbage chute, Dylan is shown staring at a box with Lionel Shrike's name on. Dylan seems to recognize that name, yet he never reveals this fact to anybody else.
Merritt throws us a clue at the beginning of the film when he's reading Dylan, noting that Dylan has "daddy issues". "Daddy issues" is right.
In Act 2, the Four Horsemen begin by asking if they are performing multiple tricks, or one big trick. The Reveal shows that this was the case for the entire film - every little trick played was part of the big trick being played... by Dylan.
When Dylan discovers the tracker in his pocket, his yell of "I was chasing myself!" becomes a lot funnier when it turns out, in searching for the Fifth Horsemen, he was doing exactly that.
While in the vault with the mirror illusion, Agent Evans hears the word "Bullshit" and starts playing an imaginary violin. Agent Cowan asks what Evans is doing and Dylan comments, "I think it's Beethoven's Concerto in D-Major". Given how Evans is hypnotized, and the music that the audience hears is only in the hypnotized person's head, how the hell could Dylan have known what piece Evans was hearing? He was the one who instructed for the piece to be planted in the first place.
Note that Dylan stops well short of the large mirror hiding the back half of the room. As the Chess Master of the whole caper, he would know the exact spot that would have given the illusion away, and makes sure that the rest of the agents don't go any further into the room.
The Reveal in the ending. Given the trailers and much of the movie, one can be forgiven for thinking it was a cat-and-mouse caper movie WITH MAGIC. The big reveal, however, was not that Rhodes was the mastermind behind the heists (even though he was). This movie is not about the heists, but rather about revenge over the death of Rhodes's father. Think about it: Bradley and the FBI kept thinking that the magicians were after money (therefore, the viewers thought so as well too). Why? Because Bradley himself was all about money and greed. In truth, there was no heist, and there was never going to be a last big hit. All of the magicians ended up with zero financial gain. Zero. That is why Bradley could not figure out Rhodes's trick in the end: Bradley was still thinking it was all about money. By using money as one big distraction, Rhodes misdirected Bradley and the latter will never figure it out.
This makes even more sense when you think about the first trick we see: a card trick involving the 7 of Diamonds. In the Minor Arcana, the Pentacles (Diamonds) represents material wealth.
This also adds another level to the film. The 7 of Pentacles represents reaching a new level, or (if predicting the future) that a future success is on its way.
Not quite zero financial gain - for at least the first two shows (Las Vegas and New Orleans), they're presumably still getting paid for performing. And if it took them a year to reach headlining in Vegas status, they would have done a lot of other shows in that time as well.
Dylan's ultimate revenge isn't just to imprison Thaddeus. It was to leave him with the one thing that would hurt him more than anything: a magic trick he couldn't debunk.
Another example on the plane involves the first version of the card trick that Alma, the Interpol agent, performs. Dylan's card ends up on the guy's lap and he says, "Nice shuffle." He actually pulled a trick in front of her and puts the card in the guy's lap. What are the odds that his card actually ended up in that guy's lap on her first card trick try because of her shuffle? Low. As a real magician, he couldn't resist messing with her simple trick in a way that wouldn't draw attention to himself.
Thaddeus said The Eye "makes any magician's wish come true." Dylan is a part of the Eye - as the Horsemen's test of worth, his one wish comes true: that the people he believes caused or profited from his father's death pay for their "crimes".
Why are the Horsemen and Dylan still set in a positive light after The Reveal? "Initiates [for the Eye] must follow a series of commands with blind obedience". The Horsemen were simply auditioning for entry into The Eye, and Dylan has a reasonable (if not entirely heroic) incentive to cause trouble for Thaddeus, Elkhorn, and Tressler, and possibly the Credit Republicain de Paris depending on whether they gained anything from his father's deathnote And if they didn't, well, the bank didn't actually suffer anything worse than the realization that the vault was full of fake money.
One plot point revolves around an organization of magicians called "The Eye". Since they're called "The Eye", maybe that's why the film is called Now You See Me.
with the King of Swords/Spades