Playing with the work of other artists could have been fun for John Tenniel too. (Of course another reason for the similarity simply could be, that the designs of the train compartmens are similar.)
Bycatch from my Snark hunt:
[left]: John Tenniel: Alice on the Train (1872)
[right]: Augustus Leopold Egg: The Travelling Companions (1862)
I found the comparison in preraphaelitesisterhood.com. If it is a pictorial reference at all, it might be a nice pun by Tenniel, but not as challenging as Henry Holiday’s conundrums.
Page from a letter (1876-01-04) by C.L. Dodgson (aka Lewis Carroll) to Henry Holiday about Holiday’s illustration to the chapter The Beaver’s Lesson. The two lines at the bottom are notes written by Henry Holiday.
I think the note is:
× L.C. forgot that “the Snark” is a tragedy and [should]
on no account be made jovial. h.h.
In the end, Carroll produced a tragicomedy.
See also: https://twitter.com/Bonnetmaker/status/1033366198535286785