Can any of you remember what you were doing at the end of 2008, when Fallout 3 was released? Don't answer on here, just think for a moment.
The reason I ask this is because that is how long Bethesda have been working on this game. And over a development time this long, everything has significance. This includes every element of what we are shown in the footage, and more importantly, the details that we are not shown. Think of the whole "200 year" fiasco, even the actual start date of post-war gameplay is being kept from us at this stage, suggesting that it's actually very important.
But going back to the question from the OP, look at what we do see before we arrive at the vault. Just before reaching the actual vault area itself, we pass a vertibird. There is also a small building behind the fence. Also, notice the crane to our right in this area. In the next shot, where we see our spouse running up onto the vault, the vertibird is now immediately behind us. Later when we emerge from the vault, the camera pans round to the left and stops at the same crane we saw earlier. Our protagonist then walks straight ahead, and is then shown reaching the gate that exits the vault area.
The area just past the crane that we are not shown after leaving the vault is the area with the vertibird. This tells us that something significant happened not only to the vertibird itself, but also those on board at the time. My own theory is that the vertibird took off shortly after the bomb dropped due to the blast doors above vault 111 having already sealed shut. The soldiers we see in this area (including one in power armor) realise that they had no choice but to find another place to take shelter, and so they attempt to take off in order to reach a military bunker. The vertibird then crashes due to very high winds following the blast, and all on board are killed.