It seems that what happens in Vegas stays in Vegas, as when I render out my video files I'm often finding frames that I cut reappearing in the final video. It's like the render is inserting the single frame after a cut before moving on to the next scene.
That happens to me sometimes too, and I don't know why. But I have found that if I zoom in to the cut, and move frame by frame across it, I see such bugs in the preview window and can fix them before rendering. I have made it a habit to do that on everything I do in Vegas before rendering. The easiest way I've found to fix it is to move the next clip up to another track and then one frame to the left, to "cover up" the errant frame.
There's another bug I have encountered with Vegas that only comes up rarely, but it is extremely annoying when it happens.... sometimes when I resize or trim a clip, it completely messes up the rest of the clip by replacing some of the frames with duplicates of nearby frames. The result is the video becoming very jerky. I haven't found a fix for that one... usually I have to delete the clip and reinsert it. I could see it happening if I stretch a clip, but it shouldn't happen just from trimming or resizing.
Vegas also renders some title font sizes very poorly... I'm guessing they probably fixed that one in a later version (I need to upgrade).