Are there reflections in the fourth dimension?

[hydrostaticequil]

If so what does the reflection look like?

 

[pinball1970]

If so what does the reflection look like?

Physicists refer to three dimensions of space and one of time usually. I am not sure what you mean by "reflection."

 

[PeroK]

What do you mean by the fourth dimension?

 

[Baluncore]

Welcome to PF.

If so what does the reflection look like?

How will you make the mirror?

A "phase conjugate mirror" might reflect EM radiation, back the way it came, in effect backwards in time. That would cause things that reflect light or radar to cancel with themselves, becoming invisible. There has been military research into the field of making things invisible, but I don't think there has been any real success.
https://en.wikipedia.org/wiki/Nonlinear_optics#Optical_phase_conjugation

 

[fresh_42]

If so what does the reflection look like?

I would define a reflection as a linear map that changes the sign in one dimension and keeps all other dimensions fixed. This is independent of the number of dimensions.