It was a bad piece of writing that had Lancelot grab the tablet and say it was the Grail. He knew other things from his character's story-i.e. Guinevere-- so he would have known that in his story (King Arthur legends) the Grail was unquestionably believed to be the cup Christ drank from at the Last Supper. No way would he have mistaken this tablet with Egyptian hieroglyphics on it for the Grail.
Actually, according to legends of which Lancelot is one, it is unclear what the grail is specifically. It is said to bestow eternal life, so the tablet could qualify in Lancelot's view.
Really you are so certain about that??? Here is the quote: "King Arthur wasted years searching for the Holy Grail. To think it was a tablet all along."
And what the other poster replied, makes perfect sense (it was crystal clear to me), while watching the film, that the reason he believes the tablet is the grail is because he suddenly realizes the tablet brings eternal life. That's when his quote came into play. "To think it was a tablet all along."
Also, remember the guy did come off as complete moron throughout the entire film. He wasn't ever paying attention to anything, or anyone, he just loved going off on quests, no questions asked, he was all in.
Did anyone on here read the Da Vinci Code? It was Mary Magdalene in that book. The grail was never described nor was it named. Indian Jones and the Last Crusade had it as a plain drinking goblet. In the Silver Chalice it was a plain drinking cup.