Yes, it must be showed or we have ridiculous discussions like this. Movies are a storytelling medium, not a painting. It either happened in the movie or it didn't. It wasn't shown, so it didn't happen. There were no clues to solve, no thinking to be needed. Get over it.
The comics medium is a storytelling medium, too, and more than enough writers and artists in the comics medium don't spell out or show everything. They often have vague sequences, or random background "noise" that doesn't seem important but in which something is happening, or they do things entirely off-panel, meaning we don't get to see it happen at all, but it still happened. I could provide examples, but I'd hope I really don't have to.
It's the same with television. Television is a storytelling medium, too, and the same things apply.
Heck, the same can even be said with prose. Something early in a novel is vague or unnoticed because it's so inconsequential or "hard to see," and yet it's something nonetheless.
But we can discount prose altogether, since comics and television are closest to "movies." And technically, movies wouldn't be so much a medium as a genre, like television, of a "visual-based" medium, or some such. But who's counting?
There are dozens upon dozens of movies out there that don't show or spell everything out, just like there are dozens of television shows and dozens of comic issues that don't. There's nothing in the definition for either mediums that everything must be shown, else it didn't happen. If it's referenced, there might be an argument because what happened will be subjective, but it can still have happened. Equally, it could not have happened, but the defining matter is not "They didn't show it, it didn't happen, KTHX."
The defining matter will be when/if it's referenced in something ahead.

The camera moves around so much, so fast during those hits, you can't actually tell where the specific shots are coming from and they were all fitted with Sabo rounds, the same firepower that took off Scorponok's tail. Also, when Starscream turns back into a jet he flies offscreen, so we actually don't know which one he really is.
I'm pretty sure that how it happens is Starscream flies off-screen, behind a building, one of the pilots goes "Where'd he go?" and then Starscream flies back in, in F22 mode, and into formation with the remaining -three- jets. And then four jets hit Megatron.
7-4=3. +SS=4. 4=boomboomMegatron.