The White Knight's Sugar Loaf Helmet

From the script:

"ALICE. What a curious helmet you've got! Is that your invention too?

WHITE KNIGHT. (Looking down proudly at his helmet, which hangs from the saddle.) Yes, but I've invented a better one than that--like a sugar loaf. When I used to wear it, if I fell off the horse, it always

touched the ground directly. So I had a very little way to fall, you see--But there was the danger of falling into it, to be sure. (Solemnly.) That happened to me once--and the worst of it was, before I could get out again, the other White Knight came and put it on. He thought it was his own helmet."

p. 60

So what is a sugar loaf?

A sugarloaf was the traditional form in which refined sugar was produced and sold until the late 19th century when granulated and cube sugars were introduced. A tall cone with a rounded top was the end product of a process that saw the dark molasses-rich raw sugar refined into white sugar.

(mawer.clara.net/usefularts.html)

Rowing Lessons with the Sheep

From the script:

"SHEEP. (Handing her a pair of knitting needles.) Can you row? 

ALICE. Yes, a little – but not on land – and not with needles –

(The needles turn into oars in her hands, and ALICE sees that they are in a little boat, gliding along between banks.)

SHEEP. (Taking up another pair of needles.) Feather!

(Thinking that this does not sound like a remark that needs any answer, ALICE says nothing, but pulls away. Every now and then the oars get stuck in the water, and will hardly come out again.)

SHEEP. (Taking more needles.) Feather! Feather! You’ll be catching a crab directly.

ALICE. (Thinking to herself.) A dear little crab! I should like that."

p. 35 - 36

Rowing Terms:

Feather: To turn the oar so that its blade is parallel with the water (opposite of square).

Crab, or Catch a Crab: A rowing error where the rower is unable to timely remove the oar blade from the water and the oar blade acts as a brake on the boat until it is removed from the water. This results in slowing the boat down. A severe crab can even eject a rower out of the shell or make the boat capsize (unlikely except in small boats). Occasionally, in a severe crab, the oar handle will knock the rower flat and end up behind him/her, in which case it is referred to as an 'over-the-head crab.'

(wikipedia.org/wiki/Rowing_terms)

As we see later on in the scene, Alice does indeed "catch a crab" when "...one of the oars gets fast in the water and won’t come out again, and the handle of it catches [her] under the chin, and sweeps her off the seat, and down among the heap of rushes" (p. 37).

The Lion and the Unicorn

From the script: 

 "HAIGHA. They're at it again!

 WHITE KING. (Jumping up and shaking himself.) Do you call that a whisper? If you do such a thing again, I'll have you buttered! It went through and through my head like an earthquake!

 ALICE. Who are at it again?

 WHITE KING. Why the Lion and the Unicorn, of course.

 ALICE. Fighting for the crown?

 WHITE KING. Yes, to be sure, and the best of the joke is, that it's my crown all the while! Let's run and see them.

 ALICE.

  The Lion and the Unicorn were fighting for the crown: 
 The Lion beat the Unicorn all round the town. 
Some gave them white bread, some gave them brown; 
 Some gave them plum-cake and drummed them out of town."

p 50

Historical Background: 

 “The Lion and the Unicorn lyrics date from 1603 when King James VI of Scotland became James I of England unifying the Scottish and English kingdoms…The union of the two countries required a new royal coat of arms combining those of England, which featured two lions, and Scotland, whose coat of arms featured two Unicorns…A compromise was made thus the British coat of arms has one Lion and one Unicorn and the poem about "The Lion and the Unicorn" was created” (rhymes.org.uk).