Caitlyn and Rose were just as worried for the Doctor. If he didn't know what was real, they could be in real trouble quick. Then there was a bit of an 'ah-hah' light bulb in Caitlyn's head. "It has to be the air. We just walk out to an unknown planet that we can breath easily? I think we should get to the TARDIS and clear our heads. Then we can come up with a game plan for what we are going to do here." She said. Rose nods agreeing that it did make a bit of sense. She stood by the Doctor fear for his wellbeing rose in her heart again. 
"Doctor? I think Cat might be on something. Let's just go to the TARDIS for a little while." She said with a kind smile at him.