The War With Canada?
SG-1 go back to 1969 (go figure) when the solar flare hits their wormhole... or something. Daniel fails at not being a Russian spy, and Jack confessing to being an intergalactic hero before young!Hammond helps them escape because current!Hammond wrote himself a note. SG-1 bum a ride with some hippies and embrace the time and place, while heading off to find the gate in order to get home. There's some shooting and leaping and old!Cassie has to send them back to 1998 as they lept too far, meaning jack still has to pay Hammond back, with interest.
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Resource credits to: x_fei , rhcp_csi , endlessdeep , chamberten & miggy