>An Easter egg is an intentional inside joke, hidden message, or feature in an interactive work such as a computer program, video game or DVD menu screen.
The headbobbing, the camera flashing etc. are hidden hints/messages from the programmer to the player, so I'd say the term fits
Ehhh.. What's meant by "message" in that quote is usually something more like an actual textual message from a developer, like "Stormbrew was here!", not a visual cue for the game itself. Easter eggs are meta, this is not.
It's also something you have to seek out -- by going to a particular place and doing a particular thing. This is just something that happens in the game, and it happens without player triggering.
The wikipedia page agrees with me on this, as far as I can tell, if you keep reading past the first sentence (which is a summary, and as with many wikipedia summaries, is incomplete and vague). This first paragraph from the software section seems rather more useful to quote:
> In computer software, Easter eggs are secret responses that occur as a result of an undocumented set of commands. The results can vary from a simple printed message or image, to a page of programmer credits or a small videogame hidden inside an otherwise serious piece of software. Videogame cheat codes are a specific type of Easter egg, in which entering a secret command will unlock special powers or new levels for the player.
