Hi John!
One of my favorite "bloopers" is a very subtle one. It's in Humbert Allen Astredo's first scene as Nicholas Blair opposite Alexandra Moltke as Vicki. As he's saying goodbye to her, he has a line that comes out something like, "Very pleased to meet you Miss Molt ... er, Miss Winters!" If you're not very attentive, you'd miss the flub altogether, because he covers it with one of his most deliciously courtly smile.
Then there's this scene again involving Humbert, though the blooper was not at all his fault. When, as Evan Hanley, he was dismissing the "shade" of Minerva Trask (a simulacrum created through one of Evan's few workable spells--quite a clever one, actually), the director had failed to realize that Jerry Lacey, Joan Bennett, and Clarice Blackburn would need to dash ACROSS the camera on the very set where Humbert was reciting his incantation. I swear you can hear Jerry muttering "Jesus!" as he and the two ladies scamper madly across that set!
So many more I could mention... this morning I was watching an episode towards the end of the 1897 storyline where it was one of those days where EVERYTHING seemed to be going wrong. Only the magisterial Thayer David kept his cool. What a gent he was.
On the MPI blooper reel, my absolute favorite moment is the bit of footage that miraculously survived from the one time when they were supposed to have stopped tape and the camera kept running. You hear the director (maybe H. Kaplan?) yell "cut!" and Grayson Hall just glares at him and says: "WHY?" No question who was in charge on set that day!
Gothick