julia> using Compat
julia> @compat 1
1
julia> Compat.@compat 1
1
julia> @everywhere Compat.@compat 1
julia> @everywhere @compat 1
ERROR: On worker 2:
UndefVarError: @compat not defined
eval at ./boot.jl:235
eval_ew_expr at ./distributed/macros.jl:116
#106 at ./distributed/process_messages.jl:268 [inlined]
run_work_thunk at ./distributed/process_messages.jl:56
macro expansion at ./distributed/process_messages.jl:268 [inlined]
#105 at ./event.jl:73
#remotecall_fetch#141(::Array{Any,1}, ::Function, ::Function, ::Base.Distributed.Worker, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:354
remotecall_fetch(::Function, ::Base.Distributed.Worker, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:346
#remotecall_fetch#144(::Array{Any,1}, ::Function, ::Function, ::Int64, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:367
remotecall_fetch(::Function, ::Int64, ::Expr, ::Vararg{Expr,N} where N) at ./distributed/remotecall.jl:367
(::##7#9)() at ./distributed/macros.jl:102
...and 1 more exception(s).
Stacktrace:
[1] sync_end() at ./task.jl:287
[2] macro expansion at ./distributed/macros.jl:112 [inlined]
[3] anonymous at ./<missing>:?

# Para.jl
module Para
export myidentity
function myidentity(x)
return x
end
end

# mytest.jl
push!(LOAD_PATH, "D:\\Working\\temp") # This is my path
using Para
# I expect an UndefVarError here,
# using @everywhere does raise an UndefVarError here though.
println(pmap(myidentity, ['a', 'b', 'c']))

Executing julia -p 3 mytest.jl in the commandline correctly yields ['a', 'b', 'c'].

Yep, this is a bit odd. In particular the docs says:

help?> pmap
search: pmap TypeMapLevel TypeMapEntry promote_shape repmat typemax SparseMatrixCSC polygamma AbstractSparseMatrix PermutedDimsArray
pmap([::AbstractWorkerPool], f, c...; distributed=true, batch_size=1, on_error=nothing, retry_delays=[]), retry_check=nothing) -> collection
...
Note that f must be made available to all worker processes; see Code Availability and Loading Packages for details.
...