Green Element?

Hi, new here. So quick question for everyone. In the Pilot, when the Elements of Harmony are shown, there is a green element among them.  
But when our heroines use the elements, there is no green element.  
Even when their destinies are swapped, there is no green gem.  
So did one of the elements change color? If so, is it Rarity’s (Ironic as it would be, seeing as how she dislikes the color green) or Fluttershy’s element, since they both have purple/pink elements, and there is only one of those in the original set? Or is this some unknown element of harmony yet unseen?  
This is made even more confusing by the season four premiere, as the promo image of the tree of harmony shows a green element.  
But when Celestia and Luna use the elements, there is no green one.  
Sorry for asking, but this issue has been puzzling me for some time. Does anybody have an answer to this enigma?

Probably just overlooked by animators. Perhaps they colored one wrong.

Going by the position of the elements at the end of Princess TS.
 

 
The green one belonged to Fluttershy. Going by the color of the screenshot with Celestia and Luna, I would say  

I’d be inclined to say it’s an animation error as well, except it seems to be used extensively in the promo art for the show. Then again, Twi-Lion is also used extensively in promo art. Again, just a inquiry I have been meaning to inquire.

green is not a creative color

green isn’t your color

Just a mistake and not paying close enough attention to details, I’d say.

I’m going to err on the side of animation error/continuity gaff.
 
(Remember: pilots usually suffer from first-episode-itis)

Aside from Celestia having the “magic” element as part of her three, I don’t think the animators gave any thought as to which elements each Princess held. When you look at what the elements actually are, it becomes obvious that only one of the three could apply to Luna (hint: it ain’t laughter).
 
As to the Green element… same thing. Originally, the elements were supposed to form this rainbow, like in the first image, but when it became obvious that none of the ponies had a colour scheme that worked with green, that one was jettisoned in favour of pink.

@The Twelfth Doctor Whoof  
That’s just too bad. I liked the green element. Added more color than another pink/purple one.
 
On a related note, there seems to be a lack of green in the show in general. Spike is the only main character with any ounce of green on him (Not counting Rainbow’s mane), and he’s primarily purple. As for other characters that are green…Granny Smith, Lyra, and Gummy are the only ones that come to mind.

Green prints really poorly, might be part of it.

@Background Pony  
Oh, I did not know that. Interesting. I guess there could be a legitimate reason for the lack of green characters in the show. That’s just too bad, as it is my favorite color. Is that also the reason for the weird purple turf in Dragon Quest and other such instances?

@Background Pony  
Tank is a teal-colored tortoise, teal is kinda green.  
Daisy has green hair.  
Quite a few Apples have green eyes and\or hair.  
Fluttershy has teal eyes and a teal gala dress.  
One of Celestia s’ aurora-mane-stripes is teal, so are Luna s’ eyes.  
Raindrops’ hair is teal.  
Medley is completely teal, with cyan eyes.  
Merry May has a green body.  
Minty from previous gens had a mint green body.

@Squirmy Hooves  
That is a lot of Teal. Also I’m Pretty sure that Lightning Dust is Teal as well. But most of these ponies are background ponies. Like I was saying, there seems to be a lack of pure green in main characters. We have plenty of Pink and Purple though.

@Background Pony  
Yup, there is a lot of pink and purple. But the only reason you think the pink is too much, it’s because Pinkie Pie is in there- her body is covered in dark pink hair and she has a fuchsia mane. But seriously, even though ponies can have all colors, Twilight s’ coat is lavender, so is Spike s’ scales, and Rarity s’ hair.
 
I think this is because people like pinks and purples more (are actraccted more to it) and also because it looks girlier.
 
And the character’s color schemes were based on past ponies from previous generations.
 
Pinkie Pie is suppose to be mostly dark pink, Rainbow Dash has to have rainbows on her design, and blue represents the sky. Applejack s’ color scheme is based after apple cider also called applejack, Rarity is too uppity to be green, and Fluttershy works better as an yellow pony with dark pink hair, not only because she is somewhat based on Lauren Faust, but also because she is suppose to be more animal-based than plant-based.
 
Uh, and Sweetcream Scoops, Bitta Luck, and possibly other ponies, are also all green.
 
(Wonder why they did not make it so the HasbrOC\toyline ponies were the background ponies for the show. Ok, ’cept for Twinkleshine, Cherry Berry, Blossomforth, and a few others in the blindbags.)

@Squirmy Hooves  
An impressive examination of the main six’s color schemes you have right there. I guess since Pinkie is all pink and Twilight is all Purple, it would seem that these colors appear more prevalent than they actually are.
 
Color scheme wise, one thing I noticed is the overabundance of white Unicorns. You got Rarity, Sweetie, Shining Armor, Blueblood, Fancy Pants, Fleur, and the list goes on. I know Unicorns are traditionally white in legends, but when the three primary male unicorns in the series are all white (two of them with blue manes), there is a lack of variety.

@Background Pony  
Also: Twinkleshine. She is egg-shell white and has pink hair- through her hair is actually cerise, not the same dark pink as Fluttershy s’ mane.
 
Lemon Hearts is yellow with blue hair, you can say that she is lemon-colored in fact. Maybe the hearts on her flank are blue and green, but it’s still good.
 
Lyra is an all-teal pony, while Minuette is all-blue, and Sea Swirl and Amethyst Star are both purple, but Sea Swirl is more of a lavender-purple with indigo hair, and Amethyst is a warmer shade of purple.
 
So you have unicorns with white, blue, purple, teal, and yellow colored coats, at least.
 
It seems like that unicorns have cool-colored tones and colors like purples, violets, whites, and blue, while Earth Ponies tend to be more earth-toned and\or colored like fruits or flowers.
 
And pegasi run the gamut, apparently. But some of them, especially Wonderbolts, are colored like weather phenomena.

@Squirmy Hooves  
Interesting observations.  
Funny how this topic has changed from one about the elements of harmony to one about the coat colors of ponies.

@Background Pony  
Yup. Maybe the Elements of Harmony change color schemes depending on who is the current element holder- maybe the original Kindness element holder had Merry May s’ green coat, original Generosity had a fuchsia mane and eyes, and original Magic had a more lavender-ish eye and magic color than Twilight, maybe also a darker shade of Rarity s’ mane color.