(That this chapter was added by another hand has been asserted, against clear evidence to the contrary, by some late critics, chiefly because the Evangelist had concluded his part of the work with Joh 20:30, Joh 20:31. But neither in the Epistles of the New Testament, nor in other good authors, is it unusual to insert supplementary matter, and so have more than one conclusion).
Jesus showed himself again - manifested himself again.
and on this wise he manifested himself - This way of speaking shows that after His resurrection He appeared to them but occasionally, unexpectedly, and in a way quite unearthly, though yet really and corporeally.