Commings missed nearly all of training camp after breaking his left collarbone. The fifth-round pick from Georgia was put on IR with a designation to return, meaning he could return to the active roster at any time during the season.
McDougald made it through final cuts as an undrafted free agent out of Kansas, only to be waived Sunday when the Chiefs claimed seven other players off waivers.
The Chiefs also signed offensive guard Rishawn Johnson to the practice squad Tuesday. He takes the place of Rokevious Watkins, who is serving a one-game suspension for violating the NFL's substance-abuse policy.