The original idea for Hawaii Five-0's series finale, a CGI Jack Lord, already aired in the Season 7 premiere

TVLine

Showrunner Peter Lenkov wanted to end the Hawaii Five-0 reboot with the original McGarrett. "When showrunner Peter M. Lenkov first came up with the idea for the unexpected cameo, he pictured it as the series’ very final scene," reports TVLine's Matt Webb Mitovich. "But coming out of Season 6, he realized Five-0 wouldn’t be ending anytime soon, and he wanted to tackle this bit of computer trickery before another show did similar."