Some films demand a willing suspension of disbelief, expecting audiences to put aside quibbles of what’s plausible, probable or even possible. Roseanne Liang’s “Shadow in the Cloud” parts ways with credibility altogether. This insanely entertaining high-altitude horror movie — which takes place almost entirely aboard a gremlin-infested WW2-era B-17 bomber — asks you to check your internal B.S. barometers on the runway, then takes off into murky skies, testing the limits at every turn. Hardly a minute of the movie registers as “realistic,” but that hardly matters, since Liang so fully commits to its over-the-top sensibility that you’ll be clutching the armrest and grinning with glee for most of the ride.