• The bug occurred in the code responsible for verifying transaction outputs (specifically, the CheckTransaction function) in the Bitcoin Core software.
• The bug was caused by an integer overflow error. When calculating the total value of transaction outputs, the software used a 32-bit integer variable that exceeded its maximum value due to a large output value.
• As a result of the overflow, the software incorrectly treated the transaction as valid, allowing for the creation of an excessive number of bitcoins.
• The bug was fixed in Bitcoin Core version 0.3.10. The fix involved modifying the code to use a larger data type (64-bit integer) for handling transaction values, preventing similar overflow issues in the future.
• The incident did not lead to the creation of any extra bitcoins. The excessive amount that could have been generated was merely a theoretical possibility resulting from the bug.

It's important to note that this incident highlights the robustness and decentralized nature of the Bitcoin network. If you're interested in more technical information about the bug and how it was resolved, you may want to refer to the Bitcoin Core software repository.