If using Guard frequency (121.5 for civies) it would be feasible. Plus radio frequency is not limited to a geographic area. Any ARTCC could use any frequency on demand.
I work at an ARTCC, so I naturally have to criticize any aviation movie lol. Yes, guard would work. As for using any frequency on demand, not plausible.
I enjoyed it tremendously. Actually watched it on breaks while working midnight shift ATC, so was in just the right mood.