The two-minute clip, unveiled on Tuesday, comes just one month ahead of the film's release.
Woody, Buzz Lightyear, Jessie and the rest of the toys are facing a crisis when their owner, Bonnie, returns home with a new creation, Forky – who does not know the first thing about being a toy.
While the family goes on a vacation, Forky becomes lost, prompting the rest of the toys to go rescue him.
Along the way, Woody and Bo Peep encounter Duke Caboom, who introduces himself as "Canada's greatest stuntman" before launching into a series of complicated posing on his motorcycle.
Little has been revealed about Reeves's character, though Tim Allen, who voices Buzz Lightyear, told Jimmy Fallon on his Tonight Show last year that the part is "great".
“Actually, a little inside story, even [Reeves] said — gentle, wonderful guy that he is — ‘This sounds too much like Buzz Lightyear.’ And his character does have an edge to that. And the guy said, ‘So we calmed him down a little bit,’ and they reminded me his toy is only that big," he added, gesturing to indicate the toy's small size.
Toy Story 4 is out on 21 June.