Let's see, at the very least the hall would tell of a time traveler who lays a bomb at Hogwarts. In Timecop's world, the only people who time travel are those with TEC technology. It wouldn't be that hard to figure it out.
Also, the bomb haermm Check this out:
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The pod is just big enough for two people, zero cargo space. What's he gonna do, strap it to the hood?
Another thing:
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:10..."See those two red spots?" Timecop time travel is far from perfect. If Timecop tries to travel back in time thousands of times to kill every wizard in the past, yeah....
Also, at 1:02....Look how they emerge in 1994, no pod. Just them. Look at how rough the trip is. You REALLY think a bomb would survive the trip? And how do you know the bomb would even make the trip? Not to mention that a bomb small enough to fit in the pod AND powerful enough to blow up Hogwarts would never fit in the pod.
So you see, Timecop time travel is far from perfected. And transporting a bomb would be too risky.