Vincent's NT Word Studies
7. Set him thereon. But the preferable reading is ejpekaqisen, he took his seat upon.A very great multitude (o pleistov oclov). The A.V. is wrong. The reference is not to the size, but to the proportionate part of the multitude which followed him. Hence Rev., correctly, The most part of the multitude.
Their garments (eautwn). Lit., "their own garments." The disciples spread their garments on the beasts; the multitude strewed their own garments in the way. Dr. Edward Robinson, cited by Dr. Morison, speaking of the inhabitants of Bethlehem who had participated in the rebellion of 1834, says: "At that time, when some of the inhabitants were already imprisoned, and all were in deep distress, Mr. Farrar, then English consul at Damascus, was on a visit to Jerusalem, and had rode out with Mr. Nicolayson to Solomon's Pools. On their return, as they rose the ascent to enter Bethlehem, hundreds of people, male and female, met them, imploring the consul to interfere in their behalf, and afford them his protection; and all at once, by a sort of simultaneous movement, they spread their garments in the way before the horses."
The variation of tenses is not preserved in the English versions. Spread their garments, aorist tense, denoting one definite act. Cut down, spread in the way, imperfects, denoting continued action. As Jesus advanced, they kept cutting branches and spreading them, and the multitude kept crying.
Robertson's NT Word Studies
21:7 {And he sat thereon} (kai epekaqisen epanw autwn), Mark (#Mr 11:7) and Luke (#Lu 19:35) show that Jesus rode the colt. Matthew does not contradict that, referring to the garments (ta himatia) put on the colt by "them" (autwn). not to the two asses. The construction is somewhat loose, but intelligible. The garments thrown on the animals were the outer garments (himatia), Jesus "took his seat" (epekathisen, ingressive aorist active) upon the garments.