I have no doubt that UFO's exist. I've personally seen things in the sky that I couldn't identify. That being said, where do they come from and why are they here?
1. Extraterrestrials.
They came all the way across the solar system at least, if not the galaxy. Do they want to make contact or do they want to remain hidden? If they want to make contact, landing in the middle of a Super Bowl should remove all doubt. If they want to remain hidden, flying around over Peru (or Mexico City) is not the best way to go about it. There are plenty of other places to fly over where no one will notice.
2. Secret Military Aircraft.
To quote the above: "If they want to remain hidden, flying around over Peru (or Mexico City) is not the best way to go about it. There are plenty of other places to fly over inside restricted American airspace where no one will notice."
3. Natural Phenomenon not yet Understood.
And that's my problem with UFO's. There is no rationale behind them. It doesn't make any sense. Governments do things for reasons. Aliens with enough time on their hands to come all this way must have done so for a reason. Natural occurances, no matter how weird, do not need reasons. They just happen.
If these are aliens, they need to find a new hobby. They're absolutely terrible at this.