The setup for the triumphal entry is the same as for the Last Supper. Two disciples go ahead and find things just as Jesus said. How did Jesus do that? I'd like to know.
The most remarkable thing about the triumphal entry may be that Jesus is riding on an unbroken colt. You'll see other unbroken colts in rodeos!
The disciples rejoiced to praise God with a loud voice -- for all the miracles they'd seen. I'd never noticed before that Luke records their motive for rejoicing. I wonder if that explains why they were so quick to turn against Jesus. The motive of the majority was quite external.
Jesus' sadness in weeping over Jerusalem is because they did not know what was coming. His sorrow was rooted in his foreknowledge. Hmmm.
The reason Jesus was not arrested while teaching is that the people were hanging on every word!