Loving the Great Pumpkin costumes! Grim Grinning Gala is a great name too

@Background Pony #37BB  
He’s a coward! He would probably cry if he sees it! Baby Flurry Heart would enjoy it!

@DTLA
 
@Background Pony #0D2D  
What is Sunset doing in the pony world?! Why did she go through the portal that leads to Twilight’s Castle?! She was supposed to celebrate this in the human world.

Where’s Shining Armor?

@Frustration in Excelsis  
That is Twilight Sparkle and her friends on the page before they would change costumes in time for the haunted house, which would be where Twilight Sparkle getting ready to lead Sandbar, Gallus, Ocellus, Smolder, Yona and SilverStream to!
 
So the second comment I posted makes sense. Before Twilight Sparkle and her friends would get their haunted house ready, they would have to go to the Grim Grinning Gala by dressing up as Charlie Brown, Lucy, Schroeder, Shermy, Violet and Pigpen in their Halloween costumes. As for Spike, he is dressed up as a mummy. Once they are at Grim Grinning Gala, they get their haunted house set up, change costumes and Twilight Sparkle will approach her six students, which will have Sandbar, Gallus, Ocellus, Smolder, Yona and SilverStream mistake their teacher for an old beggar woman.
 
Did I forget to tell you that Charlie Brown has a younger sister named Sally?

@Background Pony #10F6  
Starlight’s wearing a generic princess costume, Sunset’s wearing a domino mask, and it doesn’t seem like Trixie is wearing anything in particular.
 
@Background Pony #10F6  
Not entirely sure how that follows from SecretTitan’s comment, but in any case the mane six turn up later in this comic dressed up as something else.  

@SecretTitan  
Then that must mean that the ponies who are dressed up as Charlie Brown, Lucy, Schroeder, Pigpen, Shermy and Violet in their Halloween costumes none other than Twilight Sparkle and her friends. I write down a list to tell you all who is who.
 
Rainbow Dash: Lucy van Pelt in her witch costume  
Rarity: Shermy in his Mr. Hyde costume  
Twilight Sparkle: Violet Grey in her ghost costume  
Pinkie Pie: Pigpen in his ghost costume (Pinkie Pie’s bedsheet got dusty)  
Fluttershy: Charlie Brown in his ghost costume (Fluttershy had a little bit of trouble with the scissors)  
Applejack: Schroeder in his ghost costume (although her ghost costume has the same raccoon hat)

@Frustration in Excelsis  
What are Starlight Glimmer, Trixie Lulamoon and Sunset Shimmer dressed up as?

@Background Pony #10F6  
She’s between Trixie and Starlight, next to the fortune teller thinking “idiots”.

@DTLA  
Really? Did you really see Sunset Shimmer?

Sunset Shimmer spotted!

Bon Bon is a trekkie and Lyra is a Star Wars fan. Wow, that is a relationship where love surpasses all differences.

All those details in the image.

@naganofan99999  
I believe so.
 
Personally I’d have made him Cherie Currie since Luna is Joan Jett.

Wow this image probably took 5 or more hours…

Is Tibbles supposed to be Elton John? Also Sunny came to visit!