User blog comment:DevonAndersen/Possible iCarly Episodes Without Carly?!?!?!/@comment-3101374-20110722060637/@comment-4184884-20110722071608

Well she is on tour so we know she can't currently be doing any filming and she said on the day before she left that the season had wrapped (at least for her.)

I think the only way she's in this episode is if they filmed her scenes prior to her leaving for tour.