Last week's episode was light years better in terms of plot and theme. This week's episode just felt like a non-stop barrage of homages with a very rudimentary plot to stitch things together.
Power Dalek Rangers - That was the very first thing I thought of when the new Daleks were revealed.
Independence Day "Taking down the alien saucer with old planes" - I half expected the last plane to kamikaze into the saucer, just like the movie.
Raising the American Flag at Iwo Jima - The raising of the British flag felt a lot like the
famous WW2 photograph. It even has the same number of soldiers raising the Union Jack.
As for the cracks, I am guessing that TARDIS is causing it.