Here are some ideas for your scenario.

**Precompressed air and electric power**

In most cases at large airports the aircraft doesn't use its [internal APU][1] (a small turbine supplying both compressed air and electric power) to save noise, pollutants and cost.

Instead there are connections to the bridge, to a truck or to the ground. For example the preconditioned air circulates in these yellow pipes:

[![Aircraft preconditioned air connection][2]][2]  

[Source][3].

**Other connections: Water, wasted water, fuel**

There can also be other connections still in place (fuel, water, wasted water). The crew would need to disconnect corresponding pipes and cables, it's possible.

**Everything must/can be disconnected**

Here is a typical ramp scene for the A320, vehicles come and leave at different times:

[![A320 ramp layout][4]][4]  

Source: [Airbus, Airport and Maintenance Planning][5].

The PIC ([pilot in command][6] of the aircraft) has extended powers when the aircraft doors are closed and it starts taxiing, this is not the case when the aircraft is not in operation. The ground support crews might not want to execute unusual pilot orders, with no push-back clearance, without their management approval, and in your scenario if the crew discloses the actual reasons for this quick departure, the departure is going to looks like the tear-bursting Kabul withdrawal. The aircraft crew can still go down the ramp using the bridge stairs (below the bridge on the first photo) to disconnect everything. 

However they must no deteriorate the sockets, and it would be dangerous to just move the plane until the connections break, e.g. the refueling nozzle would likely stay in place, allowing fuel to leak from the tank (see mechanism [here][7]), with engines running a fire is almost certain.

**Ramp obstacles**

They may also have to move some truck or generator that would stay in way, but that should be manageable in case of extreme urgency.

**Open doors, servicing panels, locking devices**

There are other points to be considered, like open doors and panels (on engines, on cargo bays, etc), chocks in place, wheels moored with mechanical anchors. All of them are manageable. You can read about these elements on the same linked Airbus document, e.g. all the connection points are described at page 204, mooring anchors at page 190.

**Risks associated with powerback**

An author including such departure in a novel would be credible, providing the crew takes the related actions. Note using reverse thrust to taxi is possible but not entirely safe.

In normal conditions it would have to be validated by the operator and the airport using OpSpec C065.


  [1]: https://blog.dviation.com/2021/06/23/how-does-it-work-auxiliary-power-units/
  [2]: https://i.sstatic.net/f4Xkh.jpg
  [3]: https://aviation.stackexchange.com/q/90451/3201
  [4]: https://i.sstatic.net/nuEuwifP.png
  [5]: https://skybrary.aero/sites/default/files/bookshelf/2369.pdf
  [6]: https://en.wikipedia.org/wiki/Pilot_in_command
  [7]: https://aviation.stackexchange.com/q/101531/3201