@Athaniar  
Yup, Cheese Sandwich and Meadow Song are the only two guys at this party. (or at least in this screenshot.)

@Athaniar  
*Left, I can’t directions.

@Background Pony #DF99  
Isn’t the pony in the upper right corner a guy too?
 
And I just now saw filly Cloudchaser and Flitter (was too focused on Lyra and Bon). That’s adorable.

I just realized something…
 
Cheese Sandwich is literally the only colt at this entire party!

Simple: The animators wanted to show 21 candles on a 2D circular cake. That was the easiest way to depict the 21 candles because they did anticipate over-analyzing bronies using maths.

@RIG  
The cake is at the very edge of the party. There’s no one behind it. Why would they put on candles that nopony could see?
 
Also, front and back are worse-defined than pony ages in MLP. Just watch Rarity’s or Fluttershy’s manes as turn their heads quickly. In many cases, all sides are front.

@RIG  
Well, the Mane 6 may be seemingly about 21, Spike a teen, and the CMC are around 7, but quite a few background ponies can vary their ages from being the same age as Big Mac\Shining Armor\Cadence one episode, and younger than the Mane 6 the next.
 
Or, one filly that we see growing up with a blank-flank Rainbow Dash and Fluttershy, is also in the present day looking the exact same, while RD looks like a twenty-something.

@Ponylooker  
 
the cake is not flat, there are more lights that you can’t see.

@Squirmy Hooves  
Except for Rainbow Dash, who, according to her cake, just turned 21.

@Ponylooker  
It’s My Little Pony, everyone is pratically “vague age”. The Mane 6 are anywhere from 14-26 depending on the episode, Spike is anywhere from 9-16, and the CMC are anywhere from 4-11.
 
Also, since dragons age through growth spurts depending on how much stuff\clutter they have, maybe ponies do the same thing, but with say, experience in a certain talent.
 
The only things we can be certain for sure is that Luna and Celestia make references to “1000 years ago”, but what does that mean in some place where two demi-goddesses move the sun and moon everyday?

Crap, this contradicts the comic, in which Cheerilee is shown to be in the same Canterlot Academy class as Shining Armor and Princess Cadance. (Which makes more sense, honestly, because she would need to do post-grad work to get her teaching certification, not to mention making her H&H Day status more poignant and making her a closer match for Big Mac. Also, ’80s fashion, anypony?) I mean, having her move to Canterlot during high school and then come back to teach in her hometown makes sense, but the age is way off.

@ROTHY  
Or maybe they will rectify this and have filly versions of Berry Punch and Carrot Top when they make another flashback. (and somehow Doctor Whooves- i do not know if it will look Tennant-like, a possible young Theta Sigma\first Doctor version, or even one of the Eighties’ Doctors.)

@P3FOYFN  
@Squirmy Hooves  
Berry Punch is a title passed down from generation to generation. It represents the pony’s ability to drink more than what should normally be healthy.

Berry Punch must be the oldest, if she is already an adult.
 
But in My Little Pony, timeline is weird, in one episode two ponies are the same age in a flashback, in another episode, one is an adult and the other a filly.
 
If there were ever flash-forwards, half of them would have a filly Dinky Doo\Ruby Pinch\Tootsie Flute, and the other half would have them as adults, maybe recolors of Colgate and Sea Swirl.

awww filly Derpy is so adorable and anyone else notice just how much she looks like dinky just makes me believe that she’s dinky’s mom even more

FLITTER AND CC AS FILLIES?!  
OH MY GOD.
 
EEEEEEEEEEEEEEEEEEEEEEE

Filly twins! Filly Derpy, Filly Bonbon, Filly Cherilee and a Filly Lyra! Pure win!

@Etherchanter  
Thank you, @Background Pony #EE58

@P3FOYFN  
She’s preserved in alcohol.
 
@somepony_you_know  
..Or Daily Motion or Vimeo…

This means Berry Punch is oooold!

@Kawa  
if only he were old enough to have a mustache.

Notice this: Cheese Sandwich wears glasses.
 
Weird Al used to. Then he took a laser to the face.

@Ferrotter  
I was thinking more along the lines of sisters or cousins but magical lesbian spawn would work too.

Oh. Mh. Ghd. So many adoranle little things! Muh duabeetus!

@Too_Offensive  
Bon-Bon is Twist’s mother.
 
…which sort of implies Lyra is her father.