Corrected entry: At the start when the explosion goes off, supposedly killing Dennis Hopper, you can see that the explosion actually forms a shape around the door frame and that the wall blows inwards. This is because of the individual charges placed around the door to make this effect work, in fact you can see the holes that they cause. In an explosion such as this, probably the first thing to happen would be for the door itself (the weakest point in the wall) to be blown off rather than the wall coming away with the door in it.
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Correction: You have to remember that this explosion was set up by Howard Payne to make it look like he died. He may have deliberately rigged the charges around the door to make it look like a bigger explosion than it actually was.
Dr Muppet
It's more likely that the OP is correct, and this is a blooper/mistake.