It is interesting to note the similitudes between the masonic ritual and the second continuation:

The son of a widow. Perceval is son of a widow

The cabinet of reflection. The first castle (the castle with the ebony door) is akin to the Cabinet of reflection in masonry, and looking inside the castle Perceval sees its same heraldic symbol (reflection). The first castle and the "cabinet of reflection" share a heraldic image akin to Perceval's, and in the cabinet, there is a mirror. 

The sun at noon. After this castle Perceval begins going around at noon and each masonic works begin at noon

The two trees. To enter in the castle of the chessborad (see below), there are two trees on the side remembering the two columns of a lodge

The chessboard. This is followed by the castle with the chessboard, paralleling the Lodge which also features a chessboard. 

The four trials. To be admitted, there are four trials: the castle of the tomb (earth), the castle of the lion (fire), the castle of air, and the amorous passage by a river (water). 

At this point, Perceval encounters the "beautiful stranger," representing his higher self.
This point marks the end of the first degree (apprentice).

The number 5. Moving forward, we start from the number five, symbolized by the city with five towers, and here Perceval progressively develops himself in a way similar to the companion level in masonry.

The seven steps.  In recogering the stag head Perceval mentions 7 elements (body, lance etc...) that are connected to the seven planets

We have after the third degree that in masonry is marked by the hiram legend. In the final phase, Perceval follows a similar path, he is now unable to die (as in the tomb episode)

the key, in the third part Perceval finds a key that permits him to sail toward his quest for verticality.

The column - It is to note that the third chamber in masonry is connected to verticality.

Ultimately, he reconstructs a divided sword, echoing the Masonic symbol of the divided key