Something like this?
julia> a = rand(2,3,5)
2Ă—3Ă—5 Array{Float64,3}:
[:, :, 1] =
0.593246 0.122574 0.77908
0.959088 0.218372 0.0891396
[:, :, 2] =
0.853314 0.171189 0.313323
0.195373 0.342458 0.642057
[:, :, 3] =
0.731841 0.951687 0.316416
0.640172 0.230144 0.701338
[:, :, 4] =
0.307028 0.172853 0.990212
0.872871 0.79285 0.214958
[:, :, 5] =
0.908459 0.441589 0.0691264
0.00724457 0.371763 0.968289
julia> a[:]
30-element Array{Float64,1}:
0.5932464540468072
0.9590878214304634
0.12257439090533429
0.21837219429910104
0.7790802711397888
0.08913955642713955
0.8533144973503481
0.19537331243008405
0.1711887305635067
0.3424581504859132
0.31332337994899184
0.6420571681929719
0.7318410592897324
â‹®
0.30702789473558245
0.8728713274277637
0.17285287148135597
0.7928495776848725
0.9902119213201215
0.2149577614800653
0.9084586968143415
0.007244565168584183
0.44158904493286766
0.3717633735726962
0.06912640765172728
0.9682886566736622