Watching this episode, I have to believe that the producers said "Say, we've got Joan Collins as a guest star. Let's remake that Star Trek episiode, 'City On The Edge Of Forever'". The problem is that instead of recreating a Star Trek classic, they wound up with a really bad Hogan's Heroes episode. Much like when you watch a two-parter and you say "You know, they really could have done that in 48 minutes", you watch this episode and say "You know, they really could have done that in 24 minutes".
The point of the episode seemed to be to give a dramatic platform to Joan Collins, and provide some depth to the Jim Phelps character. The producers succeeded on both of those fronts, but didn't make a good Mission: Impossible episode. The chase scenes were way drawn out to fill out the time, and the photography with overuse of double exposures made this seem like a romance movie.
I don't know what was up the villain...he was wearing a back brace and chin support which was never explained. It seems like the actor fell down a flight of stairs the day before filming started, and the producers said "Maybe no one will notice the ridiculous thing under his chin."
The ending, with Peter Graves cradling Joan Collins' body was straight out of City On The Edge Of Forever. It was a shame that they didn't wait four more episodes until Season Four to film this episode. That way, Leonary Nimoy could have been standing there to complete the picture.