The world is visited because it has a space gate (so only accessible by Puddle Jumper) they were looking to harvest, but when Lucius is brought back by Dr. Beckett they emerge on foot.
Dr. Beckett returns to Atlantis with Lucius but, just before Lucius materializes and steps into Atlantis, Dr. Weir reacts to him.
Teyla can be seen using her combat knife backwards when attempting to cut Dr. Beckett free from his bindings.
It's never explained how Beckett overcame the drug and made the antidote, as he was still under its influence when "rescued" by Teyla and Ronon, nor how Sheppard escaped the holding cell.
While under the influence of Lucius' "herb," a team gates to a world with a Wraith outpost. The Wraith could have seen the gate address when they returned to Atlantis.