This achievement occurs during Episode 5 - Outatime
Before you can attempt this you will first need to gain access to the ExpoOnce inside and Trixie has given you your tickets walk to the left side of the room and walk over the large glass building. (Nearest the back of the room) then:
• Interact with House of the Future Turnstile
• Interact with Potted Plant.
Now with the Potted Plant in your inventory walk over to the "Law Enforcement of the Future" booth. then:
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- Use Item on Potted Plant to equip.
• Interact with Recording Device (With Potted Plant equipped),
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- Use Item "Recording Device" to equip.
• Interact with Trixie (With Recording Device equipped.)
• Walk over to the Diver, near the entrance. (On your right)
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- Use Item "Recording Device" to equip.
• Interact with Diver (With Recording Device equipped.)
• Walk back towards the entrance.
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- Use Item "Recording Device" to equip.
• Interact with Hostile Guy (With Recording Device equipped.)
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- Use Item "Recording Device" to equip.
• Interact with Arthur McFly (With Recording Device equipped.)
Now walk back over to the Diver and talk to him and ask 'Have you seen Emmett Brown?' then walk over to the Glass house maze - Follow the guide here to avoid missing another achievement
Solution for No Backups In Back to the Future: The Game - 30th Anniversary Edition then once that is done:
• Walk over to the Diver.
• Interact with Diver.
• Dialog (Diver?): "I know who you are!"
• Dialog (Doc/Diver): "What did you do with Emmett?"
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to exit.
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- Use Item "Recording Device" to equip.
• Interact with Doc/Diver (With Recording Device equipped.)
• Walk back toward Trixie.
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- Use Item "Recording Device" to equip.
• Interact with Phone Booth (With Recording Device equipped.)
• Walk back towards the house of the future.
• Interact with House of the Future Turnstile.
• Interact with Console.
• Interact with Phone Button
• Dialog (Console): "Phone Booth of the Future"
• Dialog (Trixie): "Carl Sagan"
• Dialog (Trixie): "Can I talk to Edna?"
• Dialog (Edna): "Your dark secret..."
And the achievement is yours.
Credit to T_l_M_B_0 of PST