So I am trying to do isoelectric focusing for the first time and I made a rehydration solution with ampholytes. One of compounds I had to add was bromophenol blue, which I was only supposed to add 0.5 mg of.. but I accidentally added 5.0 mg. Would this greatly affect my results?

BPB does not serve any essential function for IEF other than visualize the run. With a very high amount you might have a slightly higher current then you would otherwise have but I am honestly unsure whether the specified amount would effect results. Depending on what you are doing as a whole, you should balance the cost of the overall experiments with the ampholytes that have been potentially wasted.