Needs A Better Title? Do We Have This One? (Tried searching, couldn't find it, also not sure if doing this right, so please forgive me.)
Our protagonists are resting, probably after running for about 10 hours straight from the villians, monster, whatever. Suddenly during their break the giant robot/monster etc. starts attacking their rest spot, seemingly out of nowhere. However the protagonists have absolutely no excuse for missing said giant monster. The thing is 100ft tall and screams like a banshee at it's lowest volume, so how the heck did they miss it?
That is a Suspiciously Stealthy Giant.
1) Cloverfield. Right at the end of the movie, where pretty much everyone has died and our three remaining characters are hiding in Central Park, Hud truns around and is face to face with the Monster. At every other point in the movie the monster is usually heard before seen, and when it is seen the thing is bloody huge. How did they miss the thing when it was right behind them?
2) Terminator Salvation. During their journey out of Los Angeles, Star, Marcus and Kyle end up in a seemingly abandon gas station. They go in, find out it isn't empty, have an argument when suddenly a Harvester (http://terminator.wikia.com/wiki/Harvester)
starts smashing up the gas station. How did they miss this thing? This thing is at least 30-40 feet tall. Perhaps it flew in on the back on the back of the Transporter ship? But still they should gave noticed that with it's huge engines. The terrain can't have concealed it because they were in the middle of desert at the time, if memory serves.
3) Killzone 3. During the 3rd level, Pyrrhus Evac, you have an on-rails turret section where you take the gun controls of a Hammer APC. During the cutscene after this section, a MAWLR (http://killzone.wikia.com/wiki/MAWLR)
, essentially a walking battleship dozens of stories high, steps on the APC you were just controlling. The characters are completely surprised by this. This thing is carrying weapons large and powerful enough to one-shot the ISA space battleships that are hanging around in low orbit above the city, and nobody saw or heard the thing coming? Admittedly the MAWLR probably stood on them by accident, not even realising the tanks were there, but considering during the level you can see these things in the background miles away, the player character has no excuse for being surprised.