It all suggests that, in addition to falsifying data, they had become so blase about falsifying data that they weren't particularly careful about it. Which suggests that they may have been falsifying data for a long time...
Perhaps, but I think a first-timer would be able to avoid those mistakes, especially if they were thinking, "oh boy, this is a really bad and risky thing I am doing here, I better double and triple check". On the other hand, if it's a normal (for you) thing you're doing, which you have to do on most of your papers, then on some days you're going to rush it.
