The first was a benchpenalty for abuse of officials with 5:18 left in the first, and the next was an unsportsmanlike call against forward Patrik Elias during a power play 3:42 into the third.
United responded well and Ronaldo, who had come off the bench, appeared to wrap things up with a penalty of his own after Tevez was brought down by Carroll.
The introduction of the Paixao twins from the bench failed to ignite the Hamilton challenge, although a penalty was awarded when Palazuelos felled Flavio.
Glasgow were having a tough time in the scrums, but a change from the replacements bench seemed to put everything in order and immediately Hayes knocked over the second penalty in the 31st minute.