As of late, I started to notice that a lot of people seem to be using the simple past tense of "to go" instead of the past participle for the past perfect, e.g., "he had went" instead of the correct "he had gone." I wasn't aware of this phenomenon so I used Google Insights for Search to see how common this is/was. I also included the present perfect to see if that showed the same pattern.
Not only has this "error" been around for years but it only applies to the past perfect and not to the present perfect. "He had went" dominates but "he has went" doesn't. Hmm... By the way, I wasn't able to check on whether this phenomenon has geographical variation because the data Google uses seem to come overwhelmingly only from the US.