The controversy arose after netizens complained that after inviting so many celebrity guests unexpectedly, they sat in the recording studio like folding screens, with none of the guests getting ample screen time. It was also pointed out that during part 2 of the special, the show spent approximately 10 minutes recapping highlights from part 1 aired last week. Guests who appeared on the show after receiving unexpected calls from the MCs and panelists included IU, DinDin, Yoo Byung Jae, Guillaume Patry, Oh Sang Jin, Block B's Park Kyung, Jo Bo Ah, Song Jae Hee, Choi Yoon Young, Lee Jin Ho, Lee Myung Hoon, and more.
A representative of 'Happy Together' stated, "It is our fault for not being considerate and dividing up screen time among the celebrities, who lent their precious time after being called by their friends for the 500th special episode. After watching the broadcast, we saw that the first 5-10 minutes of the broadcast was mostly useless material, and the staff has no excuse for such a mistake. We are apologetic to 4-5 of the guests especially, who only managed to show their faces."
The show also revealed possibly considering a new special episode by inviting the above guests again for "proper treatment".