It's the...

[Andrew Gorman]

There's a Twilight Zone episode "The Last Flight" Where a WWI RFC pilot lands his Nieuport at a USAF base ca. 1959, Chock full of B-47s.  "The Americans- I had no idea they were so advanced"  and then takes off into oblivion and redemption.  Some echoes of the William Shatner TV movie "Sole Survivor".  It's a good 'un I still remember after seeing it 50 years ago...
https://en.wikipedia.org/wiki/The_Last_Flight_(The_Twilight_Zone)

[NARSES2]

the bigger impact is foreknowledge, which lasts a short while until they change events enough.

True, we always seem to forget that little wrinkle...

Very much so

[Rick Lowe]

I had a few more thoughts about foreknowledge...

IDing the Spies/traitors (Burgess, MacLean, Philby, to name a few); how would that shape the Intelligence War?
How would the Soviet Empire look?

Add to that, when would the War have ended? Normandy was still dependent on the landing craft fleet being built, so not much you can do to quicken the building programme.
Or is there?

If they got further into Europe by VE Day, would the Eastern Bloc be smaller? Or there at all? (given a few judicious assassinations... and what about doing Mao?...)
What would a shorter war do for the amount owing on the Lend/Lease loan? Would the British Empire not have been beggared?

And the changes in attitude to Minorities and Women; in the 90's they weren't as far along as we are now, but compared to a 1940's viewpoint?
How would that have factored into the attitudes to the civilian populations of the Empire's possessions? Would they have stuck with Old Blighty after all?

The presence of an Integrated Navy - 'Light Blue' and 'Dark Blue' Sailors - and 'Light Green' and 'Dark Green' Marines - were there any 'Bumpy' Sailors/Marines/Aviators at that time?
And that leads onto the whole Sexual Revolution/Permissiveness thing - the 'Advanced Training Films' that would have been on board...

Just some random thoughts, feel free to ignore any or all of them in your backstories... 

[PR19_Kit]

'The Foresight War' by Anthony Williams may be worth a read in this context. It's been mentioned on here before, but bears a repeat.

A 21st century scientist wakes up in 1934, complete with a working laptop etc. and manages to convince the Powers That Be that he really does know what's about to happen.

The effects that just his existence has are explored, as well as other un-predictable events that occur as a result.