Deliberate mistake: While Indy is fighting the tank commander, he looks up to see them heading toward a cliff. After the tank goes over, from the time his companions look over the cliff to the time when they walk away and Indy is sitting on the ground, you can see the wind blowing in their faces. But as Indy starts to get up, the wind blows his hat toward him, which it couldn't do as his hat flew off quite a while before, and the winds would have blown it far from the cliff's edge.
Continuity mistake: When Sallah rides up to the tank to rescue Henry we see Indy toss the whip over the side of the tank, but after the tank falls over the cliff, when Indy climbs back up then walks over to stand between Henry and Sallah the whip is coiled and back in its place, hanging from his belt. Even Indy can't do that. (01:36:00 - 01:37:40)
[Over the deafening noise of ship engines.]
Indiana Jones: Are you crazy? Don't go between them!
Dr. Elsa Schneider: Go between them? Are you crazy?
Trivia: Hitler was played by the actor Michael Sheard, this was the third time he had played Hitler for film and TV. Ironically, Sheard's wife was half-Jewish.
Question: It seems that going after the grail diary in Berlin was just a plot point. Henry obviously knew about the trials in the cave by heart. The search for the holy grail has been a hobby of his for 40 years or so. Am I right?
Answer: Neither Henry or Indiana would want the diary to remain in German hands. The Nazis wanted the Grail to exploit its power. As Elsa was a German scientist, she'd already gleaned enough knowledge from Henry and Indy to utilize the information contained within the diary. The diary also contained considerable data about the Grail and its history that Henry had researched over the years and would not have memorized and wanted to retain. He would also want to pass it on to Indy.
Answer: Henry says, in response to Indy asking if he remembered the details of the trials: "I wrote them down in my diary so that I wouldn't have to remember." So, obviously he did NOT know them by heart. Also, as the other answer says, they didn't want the diary to either be in the Nazis' possession or be burned.