The alloted time and more had ellapsed when Jobi McAnuff broke City hearts with the last gasp goal.
"The ref's played six minutes of injury time apparently, he's an absolute clown but what can you do?" Johnson said.
"In the first half I had a little pop at him and he said, 'Oh give me a break I've never reffed a game before, I'm normally a fourth official'.
"How do you legislate for that? He's been given a chance but ruined it in my eyes.
"It's not a good draw, it's points lost - I'm absolutely distraught as those points were massive for us."
Cardiff now travel to Preston on Saturday, with Johnson - who scored the Bluebirds' opener at Watford - determined that they will finish the season at least in the Championship promotion play-off zone.
"We're hunting down that sixth spot, that's our target," Johnson added.
"When we get there we'll look to kick on but we will get there, don't doubt that for one minute.
"If we keep playing like that we'll push all the way."