Intervention - S4-E4
Continuity mistake: In this episode we see that Barney punched a hole in the wall next to the door because Ted broke apart a girl fight. It is supposed to be under the calendar on the right side of the door. It is also said that Ted and Robin were dating at this time. But earlier, in the episode "Wait For It..." (3-1) We see Ted going through his break up phase after Robin. One of the phases is painting the apartment, and there is no hole.