After a long philosophical chat, the Assassins turn up. Unlike everyone else there, they obviously means business. Rider offers them some wine, too.
Rider's Running Gag of flicking Waver in the head hard enough to knock him down. Constantly. Half the time for no good reason other than "you're acting kinda stupid." Or "you're acting logical." Or "I feel like flicking you in the head."
Rider and Waver's interactions in general are usually hilarious. In the course of one episode, Rider drags a visibly terrified Waver to the top of a tall suspension bridge (with poor Waver crying to get down) and when he finally does get down, Rider charges straight into the middle of a battle loudly announcing his true name and intentions with Waver staring, flabbergasted, from the back of the chariot at what an idiot his servant is being....again. Following that, as the tension escalates with Lancer and Berseker vs Saber, Rider swiftly dispels that by....running Berserker over. Literally. With his chariot. With Waver giving a pathetic "how did I get into this mess" look as he's dragged along. This troper literally had to pause the video to stop laughing.
And to one up himself even more, the next episode has Rider essentially trading the head of one of his opponents, a Heroic Spirit called from beyond the reaches of time to battle in the Holy Grail war, for a pair of pants. A pair of mega-sized pants. Why? Since he doesn't want to lose to Saber who is allowed to wander around as long as she's wearing modern day clothes. Rider in general is hilarious.
Speaking of Caster, let's step back for a moment and take a look at his obsession with Saber. A French veteran of the 100 years war, mistaking the most famous English folk hero ever, for Joan of Arc. The sheer Irony of that is so funny it hurts.
How about True Assassin being killed like an insect by Iris' giant spider construct in the Blu-Ray special episodes?