If Queen Chrysalis or any of the changelings were able to remember this, I’m sure it would really pay off for them.

I KNEW IT!!!

What are you, president of her fan club?  
–No, that would be your father.  
-Indeed, and now she’s her to **** us! In fact, she could be in this city! She could be you! She could be me! She could even b-  
(something G-rated happens)  
–What? It was obvious.
 
(I can’t be asked to assign these lines to specific characters. XD )

@SnoopyStallion
 
Nope. Cadance wasn’t there when Chrysalis saw it. Remember? And Twilight most likely didn’t tell her this small detail of the events that happened after she arrived in Canterlot.  
It contains the implication, though, that Cadance could already be replaced by Chrysalis there, when they arrive at the crystal castle.

@Background Pony #C4A0  
TL;DR

You just need to think thoroughly next time.

Lol whatever, you’re just mad because I pointed a flaw  
in your statements and another thing that I will obviously  
point out is the changelings were outside Canterlot because  
they couldn’t get in since the sphere that Shining Armor summoned  
so how will they be able to see Twilight do the Lady bugs awake infront  
of Chrysalis that was disguised as Cadance. not to mention that  
it happened a very long time ago of course there is only one changeling  
in episode 16 an already in hiding from underground and Sunburst said  
a Changeling was spotted near by. so that means they were already alerted  
to the presents of him, all I’m saying is how can a changeling transform  
into any pony when they can use the same magic that Twilight utilized  
against one of them during the battle on Canterlot. the changeling  
know’s that it would be pointless to stay around.

@Background Pony #C4A0  
well i dont care about your opinion /)³(\

Snoopystallion you have know idea what you’re talking about  
I doubt changelings will or would be able to remember what Twilight  
an Cadance did again it’s not like changelings were always hiding  
amongst them hiding as one of them and or a inanimate objects not to mention  
considering Twilight an Cadance don’t do this to often with the Lady bugs  
awake and its pretty blunt quite a few of you bronies can’t seem to grasp  
that an have a flaw with your comments.

@Background Pony #23C5  
This is the funniest thing I’ve read this week. XD

@Background Pony #23C5  
>Cadance and Twilight do a dance they did in Season 2 finale  
>hurr dem writers do not have watched show
 
Also i think Chrysalis cant comprehend good so i think she dismissed Twilight dance as silly nonsense and promptly forgot about it

@MadVillan  
If I remember correctly, was that used on unicorns to prevent them from using spells during the Equestria games.

Before the titles of E25-6 were revealed some weeks ago (I didn’t bother to memorize their names, lol), a mock-up episode list, like those that have been somewhat frequent since Volume 8/Season 5, called E25-6 “The Flurry Heart of the Swarm”, making it seem as if Chrys would return as the mane antagonist and Cadance, Shining, and other key figures in the Crystal Empire would be the mane supportings with the yet unnamed changeling from E02 and 16 acting as an indecisive antihero protagonist.
 
However, the two-parter’s actual name is too ambiguous for anypony to relatively estimate the plot until it gets its synopsis around a month before its airdate. Thorax’s presence is of course too suspect to make it not seem as if Chrys won’t return for a later episode. It should be fine, whatever the next two-parter decides to be about. ^_^

@Kamazeustra  
The actual guards tend to me rather inept, so if one of them does remember it, they’re clearly a mole of some sort.
 
Twilight doesn’t even have guards, so she’s got a different problem.

proof the new writers havent watched the show

Head-canon: Twilight Sparkle and Cadance have a magic “weirdness filter” set up on their special greeting so that it just looks like incomprehensible motions to other ponies. That way they can keep it a secret.

It’s possible that Chrysalis didn’t have any idea of what it was, thought it was some dumb weird pony thing, ignored it, and forgot about it.

The irony.

@Background Pony #9F18  
But that would still alert them of the changeling.

@PonyPon  
Or maybe it simply doesn’t work on changelings.  
Error: invalid target

@MadVillan  
I’d love to speculate on that one-time gimmick used to contrive a climax.
 
Maybe all it would do to a changeling is keep them from changing, keeping them stuck in whatever pony form they’re currently in. Maybe even keep them from feeding.

Equestria’s most advanced method of identification.
 
Remember this thing?  

 
Neither does anyone else.

A number of the guards in both capitals have seen them do this now. If their ranks were ever infiltrated this is useless. Shining at least should have thought of that.

It would be pretty cool if at least once they did their Sunshine Sunshine thing, and one of them turned out to be a changeling. It would show that they are catching on :D

@SnoopyStallion  
Perhaps ponies are too trusting, or think changelings do even less research than they tend to.