What issues were overlooked compromised or ignored by the Founding Fathers of the US?

The major flaw that the Founding Fathers did not address properly was the issue of slavery. Yes, all trade in slaves from foreign places was addressed, but the issue within the US was compromised away. A more forward idea would to gradually reduce the number of people in bondage. The other"tactic" would have been to not accept "slave states" into the new USA.

One big issue that was definitely overlooked was:

How is the Constitution to be enforced?

There is nothing in the constitution about what should happen to any politician that breaks its laws - and obviously 'good faith' is not enough.

I have not so much an answer as an extension to the question.

I wonder if the Founding Fathers contemplated homosexuality, pornography, terrorism, and weapons of mass destruction as they architected the new republic. How might foresight into these things have changed the architecture of our Constitution?

Slavery was virtually left untouched.

Being such a hot topic, the founders left it up in the air per Article I, section 9 where it states: "The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight..."

There was the "fugitive slave act" included in Article 4, section 2, clause 3 which states: "No Person held to Service or Labour in one State, under the Laws thereof, escaping into another, shall, in Consequence of any Law or Regulation therein, be discharged from such Service or Labour, but shall be delivered up on Claim of the Party to whom such Service or Labour may be due."

Also in Article I, section 2, clause 3, the 3/5 Compromise: "Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons. "