Not knowing the budget, or the scale of the operation it is difficult to provide specific suggestions. I am going to assume there is very limited budget. If the budget is larger than that then there are
stage automation companies who do this sort of thing for a living who would be more than happy to bid on the project.
Lights on board can be handled with a battery and 12V light sources. Sound would come from a battery-powered sound
system. Is it your intention to have the scene on the
ground trigger the
effect on the
wagon, or to have the
wagon operator initiate the scene from the
wagon. In either case there are any number of wireless protocols for providing a "start"
toggle. A garage door opener might suffice. Reasonable synchronization would happen from having a common starting
point and the same clocking mechanism on the
ground and on the
wagon.
If you need something more precise than that, then
SMPTE,
MIDI Timecode (
MTC) or
MIDI Show Control (
MSC) could be used to sync the audio
track and all the effects to a common clock.
SMPTE is additional data recorded on the audio
track, which means any consumer-grade
MP3 player could be used as the audio and clocking source.
Syncing over wireless requires more gear to take the clocking signal, decide what to do with it, and transmit those instructions to the
effect devices. W-DMX (google it) would allow for wireless control either from the
wagon to the
ground or from the
ground to the
wagon. You would need 1 transmitter (or receiver) per
wagon and a receiver (or transmitter) on the
ground. There are less expensive home-grown hobbyist wireless solutions using either
infrared or 900 MHz band RF. The people that do those really large christmas light displays in their front yard have built a cottage industry around that sort of gear.