In my application, there was a clerical error that I managed to correct for in my printed application in relation to the question "Have you been refused a visa for any country, including the UK, in the last 10 years?". In particular, the online application was stated "NO" but I managed to correct it in the printed form to "YES" and I gave my attached reasoning as "Missing document" with pen.
That said, apparently the online requires three more follow-up responses (country, visa type and date) which I did not managed to account for in the printed application form since they were not available to me on the paper when I was in the application center when you switched to Yes. Would this cause them significant difficulty? (I only had one refusal in the past which was a Tier 4 UK visa).
@pnuts Thanks for your comment. I have just sent the Home Office an e-mail the additional detail with regards to this matter. Anyway, I think that there should be a stamp on my passport to indicate previous the refusal and I think they can look it up on their records. My only concern is that they might start to wonder if I had any other refusals which in reality I do not have.