Wow this is adorable AND hilarious! The style is quite nice in it's self, and I don't quite see any problems with it. The shading is nice, and the entire comedy scheme isn't half bad. Of course, there is room for improvement. There always is. In my opinion, Shining isn't acting too much like shining (except for the fact that he's being a total moron.) I think you did some nice work here, and I wish there was more like this. But there is something that confuses me: Wasn't Fleur a mare? Oh well. But yeah, I like the style, the joke, and all in all; Great work!
I have to say that out of all of Monty Python's skits, I love this one the best. It is by far one of the most memorable, simply because of the absurdity of a military drill instructor letting his recruits go and do what they want to do, as opposed to having some discipline drilled into them.
That said, the fact that nearly the entire skit is rewritten, verbatim is a bit of a let down in this comic. There is a huge difference between a homage, and ripoff. The fact that the punchline of this comic rests in a line from Celestia doesn't change the Monty Python Transcript of the previous 11 panels. Joke still would have been gotten across if the idea and theme of the original skit was used in place of the actual "Marching up and Down the Square" skit.
There are two minor art problems with this comic that stand out the most. The first is a lack of different views in each panel. While I know it is common in flash animation to not change the position of the proverbial camera too much, part of the Charm of MLP is how well the show is animated and how reminiscent it is of the old Warner Brother's cartoons in terms of fluidity and camera work. That doesn't detract too much from the comic, but a simple way that the comic would have been more dynamic would have been to attempt to recreate the camera angles that were in the original MP skit.
The second is the second row of guards. I know you're trying to go for perspective here, by placing the back guards further up in the panel, however the problem is that the back guards are the same size as the front guards, which doesn't give the feeling of depth that I know you're trying to accomplishment. Very minor detail there, which is something that I know you'll be able to lick in future comics should you choose to continue creating them.
The end result as it currently stands is a hearty belly laugh. The idea of combining monty python and MLP:FiM isn't new, but doing this particular skit with Shining Armor is and for that I applaud your efforts here on making an entertaining comic.