So. I never watched the show in order until recently. Im on the late season 2 episode with the wormhole and I think I was scratching my head before with some other episodes as I thought it was two way. That episode finally made it clear it was one way. Also will add a mildly infuriating but do a community search for stargate does not bring up this community.
I dont remeber ever seeing what happens if something goes the wrong way, does that ever happen?
In one of the SG-1 episodes, the gang is stuck in some kind of underground jail where the captors just throw people and food through the gate. There’s no DHD on the jail side. So some of the prisoners try to escape by going into the wormhole but it’s the wrong way. Some also let themselves get swallowed by the woosh.
Gang escapes by using some mcguffin electric tree roots and manually dialing the gate.