At the start of the episode, you can hear the Stargate activating but after SG1 has sent their iris code. Since there was no active wormhole, they should not have been able to receive SG1's code.
Daniel Jackson mentions that the Dark Ages are responsible for humanity being held back for 800 years, stating that religion stopped scientific advancement. This is not true of the Dark Ages and is a misconception of that period. There are plenty of other reasons for the Tollan to be more advanced, such as wars between cultures, land, resources, etc, none of which Jackson posits.
When the last unconscious survivor is carried through the Stargate and placed on a stretcher, the supposedly badly hurt and unconscious Tollan grabs his helmet in order to prevent it from falling to the floor.
When Omoc first meets Hammond and SG-1, a close examination of the fastening of his suit reveals it to be a zipper, exactly like anything that would have been used on Earth.