SEE ALSO: Lee Seung Gi set to appear on 'Immortal Songs'

According to the show's rep on September 11, Lee Soon Jae, Shin Goo, Cho Jae Hyun, and Lee Do Yeop recently attended filming for the 'acting god' special with surprise appearances by Lee Seung Gi, Lee Seo Jin, Gong Hyo Jin, Han Ji Min, and Na Moon Hee.

Lee Seung Gi talked about his mentor Lee Soon Jae, sharing, "When I received word from Lee Soon Jae sunsengnim [teacher] that he arrived 1 hour earlier than the time we set, I got flustered... I was touched by how Lee Soon Jae sunsengnim passionately taught me how to act." Lee Seo Jin also recalled his experience backpacking with Lee Soon Jae and Shin Goo on 'Grandpas Over Flowers'.

Stay tuned for this episode later today at 11:15 PM KST!