So I have been watching Avengers: Earth's Mightiest Heroes on Netflix. One thing that bugs me is Tony Stark (Iron Man) has put millions into the Avenger's Mansion. It has everything that the Avengers could want and apparently everything their foes could want as well since half the time the bad guys just walk/teleport/sneak into the freaking mansion.

I mean really?!? I know its meant for kids but for comic's sake the security is appalling!

In some ways it actually makes some sense.  Tony Stark doesn't really think things through to the end.  He builds lavish and ridiculous (read: ostentatious) things and just expects them to work.  Really - taking, if we take queues from the last Iron Man film: if it wasn't for Pepper and the security guy (Happy); they likely wouldn't have a 'security' anything in the main Stark HQ office!

Comic book security...just like comic book physics and comic book magic and comic book life-and-death...is only as effective as the writers need it to be for the sake of the story.  And if you have multiple writers?  Often, what one treats as impenetrable, the other will routinely bypass completely or somehow render ineffectual.

The problem isn't the Avengers.  It's the Avengers' writers.

In one episode it show the security trying to activate then the black panther overriding it.

The other episodes the villains just walk into the Mansion. I mean right off the street through the gate and front door, didn't even have to do anything to the security.

Realistically though, the security can only be designed for things people 'know' about. If someone uses their powers to walk/teleport/fly into the mansion, that's a bit tougher to secure against without slaughtering all the geese flying overhead or making the entire place a solid block of steel.

Although you'd think there would at least be a keypad or fingerprint scanner on the front door.