Other mistake: In Finn's attempted sacrifice, there are plenty of logical inconsistencies. First, Rose's pod is to the side or behind Finn, but manages to beat Finn's pod to the cannon. The collision had a similarly high chance of killing Finn as would ramming the cannon. Finn then carries Rose back to the hideout faster than it took the speeder pods to reach the cannon.
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Suggested correction: She beat Finn's pod because she was going full speed. The force from the shock waves slowed Finn down. Crashing saved Finns life. He was going to crash to burn inside the laser if she hadn't saved him.
The other speeders were ordered to retreat. Finn was going full speed, so as to maximize damage to the cannon.