Slapsgiving - S3-E9
Revealing mistake: When Marshall slaps Barney in Slapsgiving you can see that his hand doesn't actually touch Barney's face and there is no audio to match the slap.
Revealing mistake: When Robin storms into her room with her gun, she slams the door and the entire wall shakes. (00:20:00)
Suggested correction: Depending on the location settings on his laptop, they could be giving a false reading. My laptop shows I'm in Cardiff Wales while in fact I'm nowhere near.
Ssiscool ★
The show was actually filmed on a film set in Los Angeles which is probably why the laptop says Los Angeles as the current location. This most probably slipped past the editing crew.