Plot hole: When the team manage to create the cavern with the buried stargate they send Teal'c through to drill his way out, but wouldn't it be safer (and significantly faster) to fire a missile or two through and blast their way out? They have no idea how deep the stargate is buried, or under what type of rock, so sending Teal'c with only four hours of air seems suicidal. (00:35:00)
Suggested correction: Except that sending a missile through would only cause the rocks to cave in onto the Stargate again and could possibly make it impossible to reopen the Stargate. If they could reopen it, they would just end up creating the same cavern. Not to mention the fact the danger to life on the planet if a missile did make it through and ends up exploding on the surface.
Except that if the gate is active, anything falling down on it would be destroyed, so if anything you would still end up with a cavern if material soil bound together as it was falling towards the gate, OR you would end up with a crater which would be Teal'c's objective.
It's not about the rocks being destroyed. It's about if the Stargate ends up shutting down and the rocks creating an iris, making it impossible to establish a wormhole.
Plot hole: When the team manage to cause the cavern to form over the buried stargate they send Teal'c through, but shouldn't the cavern be a vacuum? Air doesn't travel through the gate and the stuff caught in the vortex is destroyed, so Teal'c wouldn't need an oxygen mask he'd need a spacesuit. (00:35:00)