Highly Unlikely
I spent ten years working on avionics hardware and software.
And whilst I'm not saying everything is rose-coloured, I do find it very difficult to believe that the aircraft dynamics can be affected via the in-flight entertainment system network (not that it isn't worth checking periodically that this remains the case).
The control network and in-flight entertainment networks are very distinct and very different. They use very different technologies, and have very different strategies to ensure responsiveness and reliability. There certainly used to be air gaps between them, and if not air-gaps these days, the very different physical and transport layer technologies would, I understand, make it very difficult to actually connect the two kinds of networks. Regarding wireless comm's whilst there are radio data links between the aircraft and the ground, these are not accessible except by means of specific hardware complying with various ARINC specs and even then would be unable to affect the control systems directly.
As for flying sideways, most planes fly sideways to some small degree most of the time. If the air mass isn't moving exactly along the aircraft's longitudinal axis, then there will be a (probably small) velocity vector component at right angles to the longitudinal axis of the aircraft. So in a small way, in order to navigate to it's destination, it will in a sense be flying mostly forwards and at the same time a little bit sideways (and probably with some up or down too).
Finally, the process of going from white-sheet to delivered system, in high-integrity systems development, is very different from other areas of software development. The main effort is much more focused on correctness, determinism, fault detection, redundancy, graceful degradation, reliability etc,, than is true in other software development activities, so the existence, of stinky code in many areas of software development is, in my experience, a much less extant problem than in the avionics industry.
Biting the hand that feeds IT
