The wall of mountains effect results where continents collide. The Himalayas and related ranges are an example with Eurasia on one side, and India on the other.

With such mountains, you should have something that would look right as an independent continent on either side.

Some technical nits of my own:

The overall layout has a "contrived to fit the map" look. You have two very large continents that are almost exactly the same size, and centred directly opposite each other. Then you have two small continents directly opposed to each other and centred at the poles, and again the same size as each other.

Also, the small polar continents should be visible at the top and bottom of each of the equatorial maps. Assuming a Stereographic projection with equal scales, you can fake this by cutting them in half and putting a scaled up (Stereographic keeps things roughly the same shape, but makes things bigger as they diverge from the centre) half at the top or bottom of the corresponding hemisphere map.

Here's an example of faked poles in stereographic projection.

Click image for larger version.  Name: stereo-fake-pole.png  Views: 336  Size: 150.6 KB  ID: 36168

If you look carefully you can see bits that have been cut off, but as long as you stick close to the poles, it works fairly well. You can also do it backwards by scaling down the tops and bottoms of your equatorial aspect maps and pasting them over the polar maps. Instead of cutting bits off, this will leave gaps that you need to fill in.

The smaller the area covered by the polar insets, the better the illusion works. My example is fairly large with the insets covering out to 45° so as to show the errors better.