Near the beginning of the story, Mike (the milkman) states that the date is June 15, 1945. But when Sam looks at a calendar to figure out the year, it's turned to July 1945.
When Sam first leaps into a woman (S2 E4, What Price Gloria? - October 16, 1961), Al mentions to Sam that he sees Sam as the person he's leapt into. In this ep, Sam looks at Al in the uniform and recognizes him as Al right away, not "Tommy" who Al has leapt into.
In this episode's denouement, Al tells Donna that Sam doesn't remember their simul-leap. Later in the series, it's Sam who remembers when Al doesn't.
The Season 4 opener "The Leap Back" establishes the "present" as 18 September 1999, yet in Season 5 during the "Lee Harvey Oswald" two-parter the "present" is Feb. 14-16, 1999.
In opening, Al is wearing an officers uniform with crossed infantry rifles then a few frames later he has Armor devices as worn by a tanker as he was helping.
To determine the year that Al has leapt into, Sam observes a calendar open to July 1945, beginning on a Monday. However, July 1945 began on a Sunday.
Al mails a letter on June 15, 1945, to be delivered to Gooshie on September 18, 1999. However, when Gooshie talks to Sam about the brilliance of the letter, he states that it was delivered 54 years, 7 months and 6 days after it was mailed. That would have been January 21, 2000.
The Quantum Leap team tells Sam that, until he mailed his letter from the past, they had no idea where he was, and later Sam discusses how they have no information on the person Al leaped into (Captain Tom Jarrett) or what Al is doing in 1945. It is never considered simply to talk to the real Tom, who would presumably be in the Waiting Room in 1999.
At the beginning of the episode when Sam and Al simul-leap and Sam leaps back to the present, he inexplicably leaps into the Imaging Chamber. He should have leaped into the Waiting Room just as all of the other leapees had done.