Nyan asks Teal'c not to kill any of the soldiers, but to just stun them. Yet Nyan later shoots one of the soldiers twice with a Zat gun, which killed him. Teal'c explained to Nyan how the Zat gun worked so he should have known he was not stunning that soldier but killing him.
When Nyan chips away rock from the gate, he uncovers the glyph for Earth. This is the "point of origin" glyph and should be different for every Stargate.
When Daniel is being interrogated by the commander, he is in the middle cage, between Jack and Sam, but when the General calls up the live feed from the MALP in the very next scene, he is in the cage on the end. O'Neill and Carter were returning together, presumably from being interrogated. It is reasonable to assume that Daniel was placed in the end cage when Carter was removed from it.
The point of origin glyph is always at the top of the ring on the Stargate. The glyph for Earth on the Stargate found by Nyan was not at the top of the gate. The glyph for Earth will be found on every Stargate, but it is only located at the top of Earth's Stargate. So it was not a mistake for Earth's glyph to be found on this Stargate.