Bug introduced in 10.0 and persisting through 10.2 or later
This is a very weird bug and I don't really know how to reproduce it, so I'll just copy-paste the whole code
Manipulate[Row[{DensityPlot[
Cos[k Norm[{x, y} - d {0, 2}] - f Pi t]/Norm[{x, y} - d {0, 2}] +
Cos[k Norm[{x, y} - d {0, -2}] - f Pi t]/
Norm[{x, y} - d {0, -2}], {x, 0, 10}, {y, -5, 5},
PlotPoints -> 50, ImageSize -> 300, PlotTheme -> "Minimal"],
Rotate[Plot[(200 + Abs[-2 d + y]^2 + Abs[2 d + y]^2 + 2 Sqrt[(100 + Abs[-2 d + y]^2) (100 + Abs[2 d + y]^2)]Cos[k (Sqrt[100 + Abs[-2 d + y]^2] - Sqrt[100 + Abs[2 d + y]^2])])/(2 f (100 + Abs[-2 d + y]^2) (100 + Abs[2 d + y]^2)), {y, -5, 5}, ImageSize -> 280], -Pi/2]}], {t, 0, 15}, {{f, 5}, 1, 10}, {{k, 5}, 1, 10}, {{d, 1}, 0.5, 3}]
Basically this is a simulation of the double-slit interference experiment with a plot of the intensity to the right. Note that all the squares have to be written by Ctrl-6 so that they are superscript! So, the code looks like this when I open the notebook

Now try changing the PlotTheme by adding a second name, like "Monochrome". Suddenly, all brackets and parentheses go red. Upon evaluation, Mathematica spits out errors as if there are no closing brackets. It seems like everything breaks down the moment I enter the quotation marks "".
It is possible that this is a Mac-only bug.

SuperscriptBoxes misplaced, and the second quote causes it to be reinterpreted as code. Seems like a bug. Try using^instead of superscripts. Report it to Wolfram. (Caveat: I have the last beta V10, Mac OSX 10.9.4.) $\endgroup$