In the skit supporting the Global Citizen: Unite For Our Future event, Hugh Jackman can be seen chatting with his X-Men co-stars Halle Berry, Sir Patrick Stewart and Famke Janssen, 20 years on from the film's release.
But then up pops the face of Jackman's long-time faux foe Reynolds, who starred as Deadpool in X-Men Origins: Wolverine before going on to play the Merc with a Mouth in his own film series.
He says: "I hope it's OK if I join, I figured we were all in X-Men together."
The rest of the stars on the call make it clear the reunion was for cast members from the original film only, but before they know it, James McAvoy and Sophie Turner - who played younger versions of the X-Men characters in later films - have turned up too.
From there, the call rapidly disintegrates as the actors claim they have other film reunions to attend before hastily exiting the call, leaving just Jackman and Reynolds.
Reynolds says in the video: "That fell apart quickly. Guess it's just me and you, Logan... You know what that makes this a reunion for?"
With that, Liev Schreiber - who played Sabretooth in the much-derided Wolverine origins story - appears out of nowhere and exclaims: "X-Men Origins reunite! Yeah!"
The video was shared alongside a petition, which calls for a united response to the Covid-19 pandemic.
It reads: "Dear world leaders, coronavirus affects all of us.
"With no respect for borders, the pandemic has shown just how interconnected our world is, and the need for us to be united in our response.
"We are all in this together, but Covid-19 has especially affected the poorest and most vulnerable across our world. Our reaction must not reflect that same inequality.
"Please work together to urgently develop tests, treatments and vaccines against Covid-19, and ensure they're available to everyone, everywhere - not just the privileged few.
"As the virus is brought under control, I call on you to also address its dire impact on those who are already most vulnerable: make sure the progress we have seen in tackling hunger, gender inequality, education, and the climate crisis, are not lost to the hands of the pandemic.
"To do this the international organizations leading the response to this pandemic - from the WHO and Gavi, the Vaccine Alliance, to those working to alleviate hunger, support water and sanitation, and ensure quality education and more - must have the full support of governments everywhere.
"Let's build back better for a more equal future. If we work together, we can emerge from this crisis stronger, more united, and safer. Unite for our future."
You can sign the petition here.