Before I tackle the foreshadowing issue, I would like to point out something about Season III as a whole. More than any other season, it felt like there was a story arc being developed. After the events of The Crystal Empire, Twilight becomes involved in “the next level of her studies”. This is referenced at some points in the following episodes. Firstly, in the beginning of the episode Spike at Your Service, Twilight has a big pile of books to study, clearly stated to be a homework assignment from Celestia. This is quite apart from her standing arrangement “learn about friendship and report your findings”.

Secondly, in Wonderbolt Academy, we have Applejack saying to Pinkie Pie, “Why don’t we go see what Twilight is up to? I hear Celestia’s got her working on some new spells.” Celestia has never given Twilight new spells to practice before now.

 Finally, in Keep Calm and Flutter On, Discord is freed from stone for his… ugh… redemption. To keep him in line, Celestia gives the Mane 6 the Elements of Harmony. I hate this episode, to be honest, since it ruins Discord as a villain. But it does help put the Elements of Harmony in place in Twilight’s library, which is important in MMC. I would even go so far as to suggest that the reason this episode even exists is because the writers wanted to set up the finale.

 These three hints connect strongly to Magical Mystery Cure itself. The events of the episode kick off  (chronologically, if not narratively) with Celestia sending Twilight a book containing a spell, and just “coincidentally” does this after arranging for the Elements of Harmony to be in Twilight’s possession at the time.

 And then comes Magic Duel. As anti-Trixie as I am, I just have to say this episode is great for the “story arc” theory. It’s the first time the word alicorn has been said by any character, it introduces an artefact called the Alicorn Amulet, and the events in the episode can be linked to Magical Mystery Cure. Twilight solves her problem and defeats Trixie not by using magic, but by using the bond she has with her friends and working together with them. This is repeated in MMC when she uses her knowledge of her friends and their bonds to return them to normal, where it was clear that the memory spell from way back in Return of Harmony couldn’t help. There is also the fact that Celestia brings really important diplomats from Saddle Arabia to a backwater like Ponyville instead of the capital and seat of power, Canterlot, which I think points to Twilight becoming a princess, if not so much towards the alicorn part.

 Now does everything I mentioned link directly to Twilight becoming an alicorn specifically? No, I admit that it does not. What it does do, however, is provide links to the general pattern of events that happen in MMC,which culminated in Alicorn Twilight. These events, spoken lines and the use of the term alicorn provide a unity to the whole Season that makes it quite distinct from Season I or II. I’ll borrow Egoraptor’s term here and call this “theming” (By the way, I recommend you to go look up his Sequelitis review of Megaman X on YouTube. It’s some pretty funny stuff, but there is quite a lot of swearing, so be warned.)

 Now to the heart of the matter. Season III did have foreshadowing of Alicorn Twilight, mostly in The Crystal Empire. Celestia says the test Twilight undergoes in this episode will tell them whether or not she is getting close to being ready for the “next level of her studies.” She saves (well, gets Spike to save) the Crystal Empire, thereby confirming that she is ready. She is engaged with the next level of her studies throughout the rest of the Season. Is this the only interpretation of Celestia’s words? No, but I feel it’s the strongest. And if one supports the idea that the next level of her studies doesn’t start until she becomes an alicorn, that makes it a reference to Alicorn Twilight and therefore an example of foreshadowing in its own right.

 Then there is the scene where Luna and Celestia being shown together, each with their cutie marks floating behind them, and their wings half-folded in an unusual way...why, it’s almost as if their wings were being emphasized for some reason. Then Twilight is shown in the exact same way, only without wings, of course. This is a massive hint to Twilight eventually becoming an alicorn, reminiscent of the pilot’s heavy-handed foreshadowing.

The final scene of the episode, with Star Swirl the Bearded’s journal, is also pretty strong foreshadowing. We are not told outright that it is his journal, but the cover has stars and swirls on it, so you do the math. Put two and two together and it’ll add up to fourshadowing... I apologize for that horrendous pun. I won’t do it again.

The next step in the argument is usually along the lines of “Ah, but if you don’t include The Crystal Empire, there is no foreshadowing!” Apart from the question of how disregarding the first two episodes of a thirteen episode season to support your view can be considered fair and valid, I feel that that assertion is false, because of Magic Duel.

 As I stated earlier, this episode marks the first time the word alicorn is actually used in the series, which could be considered foreshadowing. The next bit here is highly subject to interpretation, but I feel I can make a case for further foreshadowing of Alicorn Twilight specifically. When Twilight sees Trixie casting age spells, she is shocked because “only the highest level unicorns” are supposed to be able to do that. Indeed, Twilight tries a similar spell and is met with only partial success. Trixie even boasts that she is “the highest level unicorn”. In the final duel, Twilight uses the magic of friendship, to “reach” an even higher level. The next level after highest level of unicorn has to be an alicorn. So her friends and her understanding of friendship allow her to reach the level of an alicorn, which is exactly what happens more literally later in the Season. Now, of course, she isn’t really casting those spells, but that doesn’t change whether or not the scene is foreshadowing, if you consider it as such.

 Maybe that’s not enough foreshadowing for some people’s tastes, but I find it quite adequate, especially if you allow The Crystal Empire to be considered, and why shouldn’t you? Altogether, it certainly is enough to counter the argument that Season III had no foreshadowing of either MMC or Alicorn Twilight.

 Another thought. In order for, say, A Canterlot Wedding to be foreshadowed as much as MMC was, we’d need four episodes with a significant degree of foreshadowing of events in the episode itself before it aired. We didn’t get them. Looking just at the no foreshadowing argument, ACW was objectively far more poorly written than MMC was. At least they took a full two episodes to develop the story, which they sadly didn’t do with MMC. But more about that will have to wait until I review that episode itself.

 Some people say Season III didn’t develop Twilight’s character sufficiently to account for her being able to ascend to alicorn status. But why limit it to Season III? Twilight has been developing since the beginning of the series. So it shouldn’t be a case of 12 episodes of development or lack of it to consider, but 64. And she has developed over the course of the series. Many series end by episode 52. Alicorn Twilight was “too soon”? Hardly.

 There is a bit less to go on here than there is in the Plot Development section, but even in Season III, Twilight develops as a character. In The Crystal Empire, she learns two very important lessons: that one should act for the good of others and not just look out for one’s own best interests, and that a good leader sometimes has to delegate responsibility in order to win the day. Both good lessons for a future princess to learn.

 Another mention of Magic Duel: Some of what I said in the above section is relevant here as well. Twilight learns that using magic won’t solve all her problems, and that she needs to rely on her friends and their relationships sometimes instead. Lesson learned?

 The other episode that needs a mention is Games Ponies Play. One scene shows that Twilight’s magic is getting more powerful. After Rainbow talks about how Cloudsdale lost its bid for the Equestria Games, Twilight gets impatient and casually levitates all of her friends to pull them off-screen. And she still has control and power left over to return the dropped flag to the Crystal Pony filly. Contrast this with TCE where she levitates herself, and Magic Duel, where she levitates a bevy of Fluttershy’s critters and moves them around in a figure of 8 shape. So there is clear progression in Twilight’s magical abilities within the Season itself. There is also development with Twilight learning a new coping mechanism from Cadence, which she uses to calm herself down when things start going wrong. Okay, it sort of fails her towards the end, but she doesn’t go (pardon the phrase) bugfuck crazy like she did in previous episodes.

 So while not every episode developed Twilight’s character or abilities during the season, there certainly were some points where we can see a progression. Is it enough? I think so, although nobody has to feel the same way about it.