1. Titanic could have been constructed with a double hull. The technology to construct double hulls was available; SS Great Eastern had been launched with a complete double hull over 50 years earlier, in 1858. In a classic failure of risk management, Titanic's manufacturers, alongside with most shipbuilders at the time, considered a full double hull an unnecessary expense, being satisfied with a double bottom instead. This all changed after the disaster, with liners everywhere being refitted with full double hulls. Suddenly the expense didn't seem to matter so much.
2. The quality of the riveting and steel plates could have been better. In the present day, ship plates are welded together using oxyacetelene torches. This technology was unvailable in Titanic's time. Instead, Titanic's