Does Argothian Elder and Maze of Ith really produce infinite mana during the attack phase?
You don't need to tap them simultaneously for this to work. Once you have declared Argothian Elder as an attacker, you can do the following:

1: Tap Maze of Ith to untap Argothian Elder

2: Tap Argothian Elder to untap Maze of Ith and another land.

3: Tap that other land for mana.

4: Repeat as much as you want.