ReekyBullet and
Houkai are correct with the math, and
Vixen points out correctly that it's often planes are the most easily identifiable replay bug. The replay isn't a video that runs - it's a real-time reconstruction of the battle that happened. If the replay gets off track, and something (like a plane) is destroyed earlier than it should be, it could cause additional planes to appear later in the replay, since in the battle log, there is a note that a [previously destroyed] plane should be deployed.
The team is looking into bug fixes and improvements to replays!