Die Glocke and other stuff was expecting in Indy 5 (but didnt happen)
Die Glocke/The Nazi Bell - early rumours were that the intriguing Die Glocke would be the McGuffin and was assumed to be the way timetravel would happen to try to change the outcome of WW2. im abit suprised it didnt get a mention in the actual movie. i.e. Voller couldve said hed tried unsuccesfully to do timetravel with Die Glocke before focusing on the Dial
https://boundingintocomics.com/2021/06/24/indiana-jones-5-title-and-plot-allegedly-leaks/
https://infinityexplorers.com/die-glocke
Nazi Occult/dark forces stuff - maybe a trip to the Owl Mountains/Hitlers Stonehenge etc
The Nazis and Vollers involvement in the moon landing stuff/Operation Paperclip would've figured more (Nazi moon base type stuff)
BTTF2/Avengers Endgame/Flash style time travel of revisiting previous films - pretty sure there were rumours Indy would encounter his younger 'Raiders' self (which i guess couldve happened had they gone back to 1939) and maybe even in one or more of the previous movies (Raiders or Last Crusade)
Atlantis - i can not believe they didnt do Atlantis for this or the last one. in fact at one point in this movie i thought they were gonna go Atlantis ..but nope. i guess Lucasfilm figured Atlantis was 'done' with the Fate of Atlantis video game/comic book
Sean Connery CG deaged scene - maybe wed see a flashback of 007 era Connery with Young Indy River Phoenix (and a more fitting cinematic send off than 2003s League of Extraordinary Gentlemen)
Shia cameo - was kind of a shock to find out hed been killed in 'nam (bit like Ben in TFA - Ford dosnt have much luck with his offspring in these legacy sequels lol.. only Blade Runner, maybe)
More pop culture references (NYC/moon parade) - Bond film showing on a cinema featuring the poster (the Bond film of 1969 was OHMSS but wasn't until December and parade was August 13, so maybe a teaser poster, or if wanted a Connery Bond film could be a rerelease), Star Trek showing on TV as Indy is still part Paramount (final Trek ep transmitted in June 1969 , but there'd be reruns..maybe a time travel ep like City on The Edge of Forever as a foreshadow.. )